The 2018 fiscal year is not over for another month, but apprehensions at the southwest border have already eclipsed the number seen in FY 2017.
Customs and Border Protection (CBP) released the August numbers in the "Southwest Border Migration FY 2018" report. The report counts the number of individuals caught attempting to illegally enter the United States from Mexico, and is widely used as a tool measuring illegal inflows into the country.
Between October 2017 and August 2018, CBP apprehended 355,470 individuals trying to illegally enter the United States. In the entirety of FY 2017 (October 2016 to September 2017), CBP only apprehended 303,916 aliens.
By looking at a combined figure of FY 2017 and the year-to-date FY 2018 numbers it is clear that any "Trump effect" slowing illegal immigration has eroded. In CBP's own words: "[T]he August apprehension numbers are a clear indicator that the migration flows are responding to gaps in our nation's legal framework."
Figure 1. SW Border Apprehensions, FY 2017 to YTD FY 2018
Any discernible "Trump effect" took place between October 2016 and April 2017 — which would include the first four months of the Trump administration. The theory went that by his fiery rhetoric alone, Trump would encourage would-be illegal immigrants from making the journey to the Southwest border. Given the increasing rise of apprehensions at the border, that theory looks to be wishful thinking.
What's more, it appears that any lasting effect of the administration's short lived "zero tolerance" policy from May to June has subsided as apprehensions rose. Indeed, family unit apprehensions rose sharply between July and August — a growth of 27.6 percent.
Figure 2. Family Unit Apprehensions, FY 2017 to YTD FY 2018
Figure 3. Unaccompanied Alien Children (UAC) Apprehensions,
In a written statement to the Washington Post, Department of Homeland Security (DHS) spokesman Tyler Q. Houlton said that "Smugglers and traffickers understand our broken immigration laws better than most and know that if a family unit illegally enters the U.S. they are likely to be released into the interior. We know that the vast majority of family units who have been released, despite having no right to remain in any legal status, fail to ever depart or be removed."
Regardless of DHS actions, this will continue until Congress passes legislation to plug the legal loopholes that drive the catch-and-release phenomenon.