The apportionment of seats in the U.S. House of Representatives and votes in the Electoral College to each state is a zero-sum system; by adding more population to some states rather than others, immigration significantly redistributes political power in Washington.
This analysis shows that the total foreign-born or immigrant population (legal and illegal) had a significant impact on the distribution of House seats in 2020, which will increase further by 2030 if immigration continues at its current rapid pace. The redistribution of House seats is primarily due to legal immigrants, who make up roughly three-fourths of the total foreign-born included in the census, not illegal immigrants. Immigration tends to redistribute seats to Democratic-leaning states and away from Republican and battleground states, though the partisan impact may become more attenuated over time. This analysis only includes those foreign-born residents, legal or illegal, counted in the decennial census; those missed by the census have no impact on apportionment.
(A companion piece to this report examines the related question of “How Non-Citizens Impact Political Representation and the Partisan Makeup of the U.S. House of Representatives”.)
Among All Immigrants
- The inclusion of all immigrants (legal and illegal) in the 2020 census shifted 17 House seats. If their U.S.-born minor children (<18) are included the impact rises to 22 seats. This estimate represents the cumulative impact of immigrants, not the change since the last census.
- In 2020, immigrants in Democratic-leaning states resulted in a net increase of 14 more seats than they otherwise would have, while Republican states had 10 fewer seats and battleground states had four fewer. If their U.S.-born minor children are included, Democratic states had 18 more seats, while Republican and battleground states had 12 and six fewer seats, respectively.
- If the total legal and illegal immigrant population continues to grow at the current rapid pace, we estimate that by 2030 immigrants will redistribute 22 seats, 28 seats if their U.S. children are considered.
- By 2030, immigrants in the census will cause a net gain of 10 seats for Democratic states, with a net reduction of seven and three seats for Republican and battleground states, respectively. Including immigrants’ U.S.-born minor children shows Democratic-leaning states will have a net gain of 16 seats, while Republican and battleground states will have 11 and five fewer seats, respectively.
Impact of illegal immigration
- Illegal immigrants captured in the 2020 census redistributed two seats. Adding in their U.S.-born minor children increases the redistribution to three seats.
- The presence of illegal aliens in the 2020 census did not create a net gain or loss for either party. Including immigrants’ minor children, Democratic states had a net gain of two seats, with a net loss of one seat for a Republican state and one seat for a battleground state.
- If the illegal immigrant population continues to grow at the current pace, it may redistribute seven seats by 2030. When their minor children are included, the redistribution is estimated to be nine seats, with a net gain for Democratic-leaning states of four seats. However, a projection of this kind reflects significant uncertainty.
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Introduction
Article 1, Section 2 of the U.S. Constitution requires that a census be taken every 10 years for the purpose of apportioning seats in the House of Representatives. After each decennial census every state is assigned the one seat it is required to receive, and the remaining 385 seats are allocated based on each state’s share of the total U.S. population, excluding the District of Columbia. (Congress capped the number of House members at 435 in 1929.) The distribution of votes in the Electoral College is based on House seats, with each state getting two additional votes.
Three additional seats have been automatically assigned to the District of Columbia since 1961. The total number of electoral votes is 538. After seats are apportioned, state legislatures draw congressional districts within each state. At present, all states create districts that are roughly equal in population, though it remains undetermined whether a state could draw district lines based on eligible voters alone.1
Immigrants, referred to as the “foreign-born” by the Census Bureau, include naturalized citizens, as well as non-citizens such as green card holders (permanent residents), foreign students, and guestworkers.2 They also include illegal immigrants counted in the decennial census and other Census Bureau surveys. The Census Bureau is clear that illegal immigrants are included in the census and its other surveys, though some share are missed. The inclusion of the foreign-born in the census has significant political implications because congressional apportionment reflects their presence.
In this report we examine immigration’s impact on apportionment in 2020 in the U.S. House of Representatives. In addition to looking at the impact of immigration in 2020, we also examine what would happen if reapportionment occurred in 2024 and reflected the dramatic recent increase in immigration. Further, we project the impact of immigration to the next census assuming the current rapid increase in the immigrant population continues to 2030. In each case, we are reporting the cumulative impact of immigrants, not the effect since the last census. It should also be kept in mind when interpreting our results that the impact of immigration on House seats reflects only those legal and illegal immigrants included in Census Bureau data; those immigrants (and native-born) missed by the Bureau have no impact on apportionment.
While there is an absolute consensus that all U.S. citizens should be counted and included in the apportionment population, opinions vary as to whether non-citizens in general or illegal immigrants in particular should be counted when apportioning seats. This report does not explore those questions. Nor do we take a position on whether the children of illegal immigrants should be automatically granted citizenship. The goal of this analysis is simply to inform the immigration debate by reporting the impact of immigration on the apportionment of seats in the U.S. House of Representatives, and thus on votes in the Electoral College.
Findings
Overview of Apportionment. The methods section of this report explains in detail how we estimate the impact of immigration on apportionment. In short, our analysis is based on Census Bureau data from 2020 and 2024 that identifies the foreign-born and their U.S.-born minor children. For 2030, we project current trends in the growth of immigrants out to the next decennial census. To estimate the impact of immigrants and their children, we first estimate the distribution of seats with immigrants and then without. The difference represents the impact of immigration. The redistribution of seats from immigration is due both to the number of immigrants in the country as well as their uneven distribution across states. In the discussion below, we focus on the impact of all immigrants and their U.S.-born minor children, and illegal immigrants and their children. However the tables also report the impact of non-citizens (legal and illegal) as well.
The Impact of Immigration in 2020. Table 1 sums up all of our results. Focusing on 2020, it shows that immigrants in the last census redistributed 17 seats. Put a different way, if there were no immigrants in the country in 2020, 17 seats would have been distributed differently across states. Table 1 also shows that 23 states were impacted by the redistribution caused by immigrants, with 16 states experiencing a reduction of one or more seats, while seven states had at least one additional seat. We will see this pattern throughout this analysis, with the number of states that gain from immigration being smaller in number than the number of states that lose from immigration. This is because immigrants themselves are concentrated, so the gains tend to be concentrated in relatively few states compared to the reduction in seats that tend to be spread out across many more states.
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If we include the U.S.-born minor children of immigrants in 2020, Table 1 shows a redistribution of 22 seats impacting 26 states. Table 1 also shows that the inclusion of just illegal immigrants in 2020 redistributed two seats, with four states impacted. When we include their minor children, the impact increases to three seats affecting five states. We discuss illegal immigration more in the methods section of this report, but it is enough to say here that there is always significant uncertainty when estimating their inclusion in the census and their distribution across states. But we can say with certainty that legal immigrants and their progeny have a much larger impact on apportionment than illegal immigrants. This simply reflects the fact that legal immigrants are much more numerous.
Which States Gained and Lost in 2020. Table 2 (see Table 2 here) shows the specific states that gained and lost seats because of immigration in 2020. The table shows that California and New York benefit the most, with the states having eight and three extra seats, respectively, due to the inclusion of immigrants in the census. Florida has two additional seats due to immigrants and Illinois, New Jersey, Rhode Island, and Texas have one additional seat. States having one fewer seat in 2020 due to immigration are Arizona, Georgia, Michigan, Pennsylvania, Idaho, Indiana, Iowa, Kentucky, Louisiana, Missouri, North Carolina, Oklahoma, Tennessee, Utah, and West Virginia. Ohio had two fewer seats than it otherwise would have. Adding in U.S.-born children causes California to have 11 more seats than it otherwise would have had, up from eight when only the immigrants are considered, while New Jersey and Texas each gain a second seat relative to when only immigrants are considered. Arizona no longer loses a seat when the children of immigrants are considered. Wisconsin, Alabama, Mississippi, and South Carolina lose a seat when minor children are included in the analysis, while Pennsylvania and Michigan each lose a second seat.
If the Census Were Held in 2024. As we pointed out in several reports since January 2021, the overall foreign-born population has grown dramatically. To gauge the impact of this recent increase we look at Census Bureau data from the first three months of 2024 and calculate the impact of immigration on apportionment. Table 1 shows that if the census and reapportionment happened in 2024, immigrants would redistribute 19 seats across 24 states. This is an increase from the 17 seats in 2020 across 23 states. Table 2 shows that California would have eight more seats, Florida and Texas three more seats each, New York and New Jersey two more seats each, and Rhode Island one more seat in 2024 than they otherwise would have if there were no immigrants. Minnesota, Oregon, Georgia, Michigan, Pennsylvania, Wisconsin, Alabama, Indiana, Iowa, Kentucky, Louisiana, Missouri, North Carolina, Oklahoma, Tennessee, Utah, and West Virginia have one fewer seat each. Ohio would have two fewer seats due to immigrants if the census were held in 2024.
If their U.S.-born minor children are included, 26 seats are redistributed, with 30 states affected. In other words, the majority of states either would lose or gain seats in 2024 due to immigrants and their young children. This is an indication of how widespread the impact of immigration is on political representation in America. When the U.S.-born children of immigrants are considered, California gains two more seats than when only immigrants are considered, while New York, Florida, and Texas each have one additional seat. In addition, Massachusetts and Arizona each gain one seat when immigrants are included in the analysis. Pennsylvania, Ohio, and Tennessee each would lose a second seat, while Arkansas, Mississippi, South Carolina, and South Dakota also have one fewer seat.
Illegal Immigrants in 2024. Table 1 also shows that the presence of illegal immigrants by themselves would redistribute four seats if the census were held in 2024, up from two seats in 2020. Table 2 shows that California and Arizona would each have one additional seat as a result of illegal immigrants and Texas two additional seats, while Minnesota, Oregon, Ohio, and Tennessee would have one fewer seat each. The table shows that if the minor children of illegal immigrants were included, five seats would have been redistributed by illegal immigrants, with California gaining one additional seat and Utah having one fewer seat. This is hardly a trivial redistribution of political power, but it is still relatively modest compared to the impact of all immigrants discussed above.
The 2030 Census. The bottom of Table 1 shows the estimated impact of immigration in 2030. It should be emphasized that projections of this kind come with significant uncertainty because they involve projecting both the size of the immigrant population in the future and their distribution across states. Assuming current trends continue, Table 1 shows immigrants alone will redistribute 22 seats in 2030, up from 17 seats in 2020. If their U.S.-born minor children are included, they would redistribute 28 seats, compared to 22 seats redistributed in 2020. Table 2 shows California will have nine more House seats in 2030 than it would have had without immigrants. Immigrants in 2030 will also cause New Jersey and Florida to have three more seats; Massachusetts, New York, and Texas to have two more seats than they otherwise would have had; and Georgia one extra seat. Wisconsin and Ohio will have two fewer seats due to immigrants in 2030; and Colorado, Illinois, Minnesota, Oregon, Virginia, Washington, Michigan, Pennsylvania, Alabama, Arkansas, Iowa, Kentucky, Missouri, Oklahoma, South Carolina, South Dakota, Tennessee, and West Virginia one fewer seat each. Again, it should be remembered this is the cumulative impact of all immigrants in 2030, not the impact since 2020.
If the U.S.-born minor children are included in the analysis, California, Texas, Florida, New Jersey, and New York each would have one more seat compared to when only immigrants are considered, while Maryland also has one more seat. In addition, Illinois and Oregon no longer lose a seat as is the case when only immigrants are examined. Pennsylvania, Missouri, and Tennessee each lose one additional seat, compared to losing only one seat each when only immigrants are considered, while North Carolina, Arizona, Indiana, Louisiana, and Mississippi have one fewer seat each.
Illegal Immigrants in 2030. Table 1 reports that if the illegal immigrant population continues to grow at the current pace, it may redistribute seven seats by 2030, compared to two in 2020 and four in 2024. Texas and California would each have two additional seats in 2030 from illegal immigrants and Massachusetts, New Jersey, and Florida would have one additional seat. Minnesota, Ohio, Pennsylvania, South Carolina, Virginia, Washington, and Wisconsin would have one fewer seat due to illegal immigrants being included in the 2030 census. Accounting for the impact of illegal immigrants plus their U.S.-born children in 2030 will impact the distribution of nine House seats, up from three in 2020 and five seats in 2024. Relative to when only illegal immigrants themselves are considered, California gains one additional seat and Illinois and Maryland would gain one seat, while Florida no longer gains a seat, and Missouri and Oklahoma lose a seat.
Partisan Implications in 2020. Table 2 divides states based on whether they lean Democratic, Republican, or are “battleground” states. We consider the five states won by Trump in 2016 but won by Biden in 2020 as battlegrounds — Arizona, Georgia, Pennsylvania, Michigan, and Wisconsin. Table 3 summarizes the net partisan implications of the redistribution of House seats (and electoral votes) caused by immigration in 2020, 2024, and 2030. It must be remembered that in the various scenarios some Democratic or Republican states may gain while others lose so the net partisan impact can be much smaller than the overall number of the seats redistributed by immigration. In 2020, immigration clearly distributed seats toward Democratic-leaning states, with a net increase for Democratic states of 14 seats, while Republican states had 10 fewer seats, and battleground states lost four. If the minor children of immigrants are added, Democratic net gains increase to 18 seats, while Republican and battleground states would have 12 and six fewer seats, respectively. Illegal immigrants by themselves had no net partisan impact, though when their children are considered, it creates a net gain of two seats for Democratic states.
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Partisan Implications in 2024 and 2030. Table 3 shows that if the census were taken in 2024, Democratic-leaning states would have 11 more seats due to immigrants in the census, while Republican states would have a net loss of seven seats and battleground states four fewer. Including U.S-born children of immigrants results in a net gain of 15 seats for Democratic states, while Republican states have 11 fewer and battlegrounds four fewer. By 2030, we estimate that immigrants in the census will cause Democratic states to have 10 more seats than they otherwise would have, while Republican and battleground states have seven and three fewer seats, respectively. If the U.S.-born minor children of immigrants are considered, then it has the effect of increasing the congressional delegation of Democratic states by 16 in 2030, while causing Republican states to have 11 fewer seats and battlegrounds five fewer seats. Tables 2 and 3 show that the net partisan implications of immigration remain large through 2030, but are somewhat smaller in 2030 than 2020, even as immigration redistributes ever more seats.
The general pattern across all the scenarios is that the Democratic strongholds of California, New York, and New Jersey, which have very large immigrant populations, tend to gain the most political power from immigration. However, the high-immigration Republican-leaning states of Texas and Florida also tend to have larger congressional delegates due to immigration in 2020, 2024, and 2030 and this somewhat offsets Democratic gains over time. Of course, how immigration may reshape the electorate of these states in the future is not addressed here. Low-immigration Republican and battleground states in the Midwest and Upper South tend to be among the biggest losers from immigration. This is especially true of increasingly Republican Ohio, as well as Missouri, Tennessee, and West Virginia, and the battlegrounds of Pennsylvania, Michigan, and Wisconsin.
The Partisan Impact of Illegal Immigrants in 2024 and 2030. As we have already made clear, legal immigration has a much larger impact than illegal immigration because the legal population is so much larger. The same is true of the partisan impact. If the census were conducted in 2024, the inclusion of illegal immigrants would cause a net increase of one seat for a battleground state and a decrease of one seat for a Democratic state. If we include their U.S.-born minor children, Republicans now lose one state with a battleground state still gaining a seat. In 2030, the inclusion of illegal immigrants in the census would cause a net increase of one seat for Democratic and Republican states each, while battlegrounds would have two fewer seats. However, adding in the U.S.-born children of illegal immigrants changes the situation, with Democratic states having four more seats than they would have otherwise and both Republican and battleground states having two fewer seats each.
Representing Non-Citizens in Congress. Although not a central focus of this report, one of the unavoidable consequences of immigration’s impact on reapportionment is that it takes seats and political representation away from low-immigration states comprised largely of American citizens in order to give representation to high-immigration states with large non-citizen populations. Section 2 of the 14th Amendment to the U.S. Constitution states that “Representatives shall be apportioned among the several States according to their respective numbers, counting the whole number of persons in each State.” This has generally been interpreted to mean all individuals, not just citizens, are included when seats are apportioned. It is possible the Supreme Court would approve an interpretation of this provision allowing states to apportion seats based on citizenship. Or perhaps allow them to draw district lines based on citizenship. Of course, the Constitution could be amended to exclude non-citizens from apportionment, bypassing the Supreme Court. But as already made clear, at present all non-citizens including illegal immigrants are included in the apportionment population.
Reducing the Representation of Citizens. In the companion study to this report we look at the distribution of non-citizens across districts between and within states and find very large differences in the number of voting-age citizens in high vs. low immigration areas of the country. For the purposes of this study, it is enough to note the redistribution of political influence away from American citizens is significant between states. Consider the case of Ohio, which has a relatively large population, but relatively few immigrants. In 2020, the state had two fewer seats due to immigration. In that same year, 97 percent of residents in the Buckeye state were U.S. citizens. In contrast, in California, which had eight more seats than it otherwise would have had due to the presence of immigrants, only 87 percent of the state’s population were American citizens.
Non-citizens cannot vote in federal elections, serve on juries, or work for the federal government in most cases. Many non-citizens, including foreign students, guestworkers, and illegal immigrants also may not make campaign contributions. Thus, it may seem odd that they are “represented” in Congress. This is especially true because the majority of non-citizens in the country are either illegal immigrants or temporary visitors such as foreign students or guestworkers.3 While one can at least argue that legal permanent residents who have not naturalized are entitled to representation in Congress because they are future Americans, illegal aliens and temporary visitors can make no such claim.
Conclusion
If immigrants were evenly spread throughout the country, they would have no impact on the distribution of House seats. However, immigrants have always been concentrated in some areas, and that is still true today. Of course, immigrants do tend to become more dispersed over time, but it is a very gradual process. In 2020, for example, the top six states accounted for about 61 percent of all immigrants, but only 39 percent of the nation’s total population. In early 2024, the top six states of immigrant settlement still accounted for about 61 of the foreign born. Because family relationships and existing cultural ties largely determine where immigrants settle, new arrivals are likely to continue to arrive in areas where there are already large existing immigrant populations. As a result, for the foreseeable future immigrants will continue to be relatively concentrated and this means their presence will redistribute seats in the U.S. House of Representatives and votes in the Electoral College.
The redistributive effects of immigration are not just a result of concentration, but also partly depend on immigrants’ share of the total population. A very large immigrant population, even if it becomes more dispersed, can still have a significant impact on the distribution of House seats and Electoral College votes. As long as the number of immigrants (legal and illegal) entering the country remains very high, immigration will almost certainly continue to redistribute political representation.
It is important, then, when making decisions regarding immigration policy, to take into account not only the economic, fiscal, cultural, and demographic impacts of immigration, but also the political impact, part of which is the realignment of power in Congress away from states receiving relatively few immigrants. This redistribution exists regardless of whether and how immigrants themselves vote and will continue to increase if immigration continues at its current rapid pace. In addition to this realignment, careful consideration should also be given to the loss of representation suffered by citizens in low-immigration states so states with large non-citizen populations can have more political representation.
The impact of immigration on redistribution is primarily due to legal immigration, not illegal immigration. So, for example, in 2020 all foreign-born residents in the U.S. redistributed 17 seats in the House of Representatives, while illegal immigrants alone redistributed two seats. If the census were held in 2024, we estimate the impact of illegal immigration would grow to four seats, which, while certainly significant, it is still a good deal less than the 19 seats we estimate would be redistributed by the presence of all immigrants. This is not surprising because even though there is a great deal of evidence that illegal immigration has surged dramatically in the last three years, legal immigrants are still much more numerous.
Since the amount of redistribution is a direct consequence of the level of immigration, a more moderate level of legal and illegal immigration would produce less immigration-based reapportionment. Given the apparent remoteness of the other effects of immigration on low-immigrant states, citizens of such states and their elected representatives may wish to consider the political costs of immigration to areas of the country receiving relatively few immigrants.
Methods
Method for Estimating the Impact of Immigration on Apportionment
While the Constitution requires the reapportionment of seats in the U.S. House of Representatives after each decennial census, it does not specify the exact method of apportionment. The Method of Equal Proportions has been used since the 1940 census, including in 2020.4 This analysis assumes that method would be used in our 2024 and 2030 scenarios. Our basic approach, as described in more detail below, is to first calculate a baseline apportionment population for each state and then compare a baseline apportionment of seats to one when the population of interest is removed. The Appendix tables show the populations used for each of our scenarios.
Estimating Immigration’s Impact in 2020. To estimate the impact of immigration in 2020 we use the actual apportionment population in 2020 as a baseline. We then remove the population of interest (e.g. all immigrants or non-citizens or the minor children of immigrants) from the baseline estimates and then recalculate the distribution of House seats. The difference between the number of seats in the baseline and the distribution once the population of interest is removed represents the effect of immigration. As was the case in 2010, the decennial census in 2020 did not ask any citizenship questions. Therefore, we use the Census Bureau’s annual American Community Survey (ACS), which asks respondent’s citizenship. Unfortunately, due to Covid-related disruptions the bureau stated that the 2020 ACS did not meet their quality standards. For this reason, to estimate the impact of immigration in 2020, we average the 2019 and 2021 ACS to arrive at a reasonable estimate of the foreign-born and non-citizen populations in 2020.
To estimate the impact of U.S.-born minor (<18) children we use the March, April, and May Current Population Survey from 2021 and 2019 CPS averaged together.5 Like the ACS, we use the 2019 and 2021 CPS to avoid problems with the data in 2020 due to Covid-19. We confine the analysis only to children born in the United States to foreign-born fathers. The CPS, while smaller than the ACS, is still a large survey and allows for this type of analysis because it specifically asks respondents, including children, about parental birthplace, which is not the case for the ACS.
Estimating Immigration’s Impact in 2024. To create updated baseline apportionment populations for each state — which simulates what would happen if the census were conducted in 2024 — we use a combined three-month sample of the January, February, and March 2024 CPS. (The ACS is not yet available for 2024.) We add to this population the institutionalized population from the 2022 ACS and the Federally Affiliated Overseas Population (FAOP), neither of which is included in the CPS.6 We then compare the apportionment of House seats using this baseline population for each state to the apportionment of seats when the foreign-born, non-citizens, and children of immigrants are removed.
Estimating Immigration’s Impact in 2030. To create a baseline population by state in 2030 we use the Census Bureau’s population estimate by state from 2020 to 2023 and assume a linear projection to 2030 for each state’s total population. We add to this population the FAOP population to create a 2030 baseline apportionment population.7 We use the growth trend of the foreign-born and non-citizen populations from January 2021 to March 2024 in the CPS to create our estimate for the foreign-born in April 2030. We then remove these populations from our baseline and recalculate the apportionment of House seats. We also project the number of U.S.-born children of all immigrants and non-citizens in 2030 using this same approach. Of course, it is far from certain the foreign-born population will continue to grow at the current rate. Our results should therefore not be seen as a prediction, but rather as an indication of what might happen if current trends continue.
Estimating the Impact of Illegal Immigration in 2020. Estimating illegal immigration in the census is always difficult. When the Center for Immigration Studies last estimated the illegal immigrant population we felt it was not possible to do so for 2020 given all the problems with data collection during the 2020 pandemic. The Center for Migration Studies (CMS) has an estimate for that year, so we use their estimate. Moreover, unlike the government’s estimate of illegal immigrants, CMS has estimates of the illegal population in all 50 states, making it possible to estimate the impact on apportionment of illegal immigrants in 2020.8 We then take the actual 2020 apportionment population, remove illegal immigrants, and recalculate the distribution of House seats. We do the same for their U.S.-born children.9
Estimating the Impact of Illegal Immigration in 2024. We use the same 2024 baseline apportionment populations for illegal aliens as we described above when we estimate the impact of all immigrants. Our illegal immigrant population for 2024 is based on our analysis of the January, February, and March CPS. We estimate based on those months a total illegal immigrant population in the data of 13.6 million. As discussed in a prior paper, our approach is based on estimating the legal immigrant population using administrative data and estimates of outmigration and deaths. We then subtract this population from the immigrant population in the data to estimate illegal immigrants included in the survey. Currently, we do not yet have a fully developed model for distributing illegal immigrants across states. We therefore distribute illegal immigrants across states based on a surrogate population of non-citizens.10 For the U.S.-born children of illegal immigrants, we estimate a total population of 5.7 million and distribute them across states using the same surrogate population.11
Estimating the Impact of Illegal Immigration in 2030. We use the same 2030 baseline apportionment populations described above when we estimate the impact of all immigrants. For illegal immigrants, our preliminary estimate for the first quarter of each year from 2021 to 2024 are as follows: 10.0 million in 2021, 11.2 million in 2022, 12.3 million in 2023, and 13.6 million in 2024. (This is our best estimate of only illegal immigrants captured in Census Bureau data, not the total size of the illegal immigrant population.) If we project this growth rate out to the first part of 2030 using a linear function, we get a total illegal population of 20.7 million. We then distribute this total across states, again using a surrogate population.12 For the U.S.-born minor children of illegal immigrants in 2030 we use the state distribution of the illegal immigrant population in 2030 discussed above and then also assume that the ratio of U.S.-born minor children is the same as in 2024.13
End Notes
1 In terms of drawing district lines within states, the Supreme Court ruled in Evenwel v. Abbott (2016) that states may draw House district lines by total population, but it did not indicate if this is required. So at present it remains undetermined whether a state could draw district lines based on eligible voters, though to do so it would need citizenship data for all persons. The 1950 census was the last time all respondents were asked their citizenship, though the question certainly could be added back into the census.
2 The term “immigrant” has a specific meaning in U.S. immigration law, which is all those inspected and admitted as lawful permanent residents (green card holders). In this analysis, we use the term “immigrant” in the non-technical sense to mean all those who were not U.S. citizens at birth.
3 As part of its estimate of illegal immigrants, the government estimates that in 2022 there were 2.8 million long-term temporary visitors in the country, including guestworkers, foreign students, cultural exchange visitors, and foreign diplomats. (See Table A1-1 in that report.) This number is relatively stable. The table also shows that there were 11 million illegal immigrants in the country at the start of 2022, with 390,000 not in the Census Bureau data. Adding the 2.8 million long-term temporary visa holders to 10.6 million illegal immigrants in the Census Bureau data shows a total of 13.4 million non-citizens who are not permanent residents. The 2022 ACS shows a total of 21.5 million total non-citizens in the country in that year. A combined sample of the monthly CPS for June, July, and August in that year shows 23.8 million non-citizens. It is not clear why the CPS shows a larger number of non-citizens, though we have discussed this issue in prior studies. Even so, these numbers imply that somewhat more than half of non-citizens included in Census Bureau data (ACS or CPS) are either long-term temporary visitors or illegal immigrants.
4 The Census Bureau has a detailed explanation of how congressional apportionment works here.
5 We confine the analysis to children born in the United States to foreign-born fathers.
6 In addition to the resident population, the apportionment population in each state includes U.S. military personnel and federal employees living overseas, plus their dependents. In 2020, this population was 1.04 million. The CPS includes most of the resident population but not those in institutions (primarily nursing homes and prisons). For this reason, the number institutionalized, which does not change that much from year to year, has to be included in this analysis.
7 We do not have a good way of projecting the overseas population to 2030 so we are forced to rely on the figures from 2020. However, the overseas population in 2020 represented less than 0.5 percent of the total population and it is spread across the country; its distribution across states is in very rough proportion to each state’s resident population, so it does not have a large impact on apportionment. For example, in 2020 excluding the overseas population would have made no difference to the apportionment of House seats.
8 Unfortunately, CMS has not published figures for every state based on 2020 data. They have estimates of the illegal immigrant population in the 15 top states, accounting for 82 percent of the estimated illegal population in 2020. See Table 3 in this publication. For the rest of the illegal immigrant population, we use their 2019 estimate of the illegal immigrant population by state. CMS estimates a 16.8 percent undercount of illegal immigrants in the 2020 ACS and a 6.8 percent undercount in the 2019 ACS. We adjust downward their state estimates on these estimates. As already mentioned, the Census Bureau reported significant problems with the 2020 ACS and for this reason the undercount was much larger in 2020 than 2019.
9 We estimate a total number of U.S.-born children of illegal-immigrant fathers based on the CPS and prior research of 4.5 million. We distribute these U.S.-born children across states based on CMS’ estimate of illegal immigrants by state.
10 We use non-citizens from Latin America (excluding Cuba) who indicated they arrived in 1980 or later who do not have a bachelor’s degree. This population significantly overlaps with illegal immigrants.
11 We use the U.S.-born children of non-citizens from Latin America (excluding Cuba) who indicated they arrived in 1980 or later living in households headed by someone without a bachelor’s degree.
12 We use the distribution of non-citizens from Latin America (excluding Cuba) who indicated they arrived in 1980 or later without a bachelor’s degree. We take the state growth in this population from January 2021 to March 2024 and then project out the growth of this population to 2030 using a linear model.
13 As discussed, for 2024 we estimate 13.6 million illegal immigrants and 5.7 million U.S.-born children for a ratio of 1 to .42. We assume this ratio holds steady to 2030, creating a total number of U.S.-born minor children whose estimate will be 8.7 million by that year. There are two main reasons we think this ratio is unlikely to change much by 2030. First, although the illegal immigrant population will have risen significantly by the time of the next census, some of their children turn 18 every year, creating a limit on how fast this population can grow. Second, as is the case in 2024, a significant share of illegal immigrants in 2030 will still be relatively recent arrivals who have not yet had time to have a child in the United States.