Given the alphanumeric soup of the temporary alien worker programs, it may be helpful to identity the H programs, all of which have some to a lot of Department of Labor involvement. (In addition to these categories, there are more than a score of other visas that allow alien holders to work in the United States, such as F-1 and J-1).
Shown below are sketches of the six DoL-related programs. The admissions data, which are reasonably consistent across categories, are shown as a rough proxy for the size of the programs. These numbers should not be confused with population estimates for each class; there are, for instance, probably close to a million H-1Bs working in the United States at any given moment.
|Definition of Worker
|Admissions FY 2013
|College graduates, often working for IT firms
|The largest and most controversial of these programs
|Virtually a dead letter
|Seasonal farm workers
|Used more on the East Coast than in the West
|Unskilled, non-farm workers
|Largely outdoor workers: landscaping, forestry, etc.
|A tiny program that attracts little attention
|Spouses of aliens in the categories listed above; most are related to H-1Bs
|Only a minority of the H-4s (some spouses of senior H-1Bs) can now work legally
Sources: The numbers are from Table 25, Yearbook of Immigration Statistics, 2013. The definitions and notes are by the author.
* Includes eight H-1B1s, who are H-1B-type workers from Chile and Singapore.
Three of the larger programs (H-1B, H-2A, and H-2B) are designed to provide employers with workers at below-market wages, although employers using them always talk in terms of "shortages" of needed workers. All of these programs involve temporary visas, of differing lengths of time; none lead directly to immigrant status, but the H-1B program can be used as a way station on the road to a green card for some.
There are differences as well. For example, the H-2A program, alone of the six, requires employers to house the workers. Similarly, the brand-new program for H-4 workers is the only one in which the worker is not tied to an employer. The Department of Labor's role in the H-4 program, by the way, is an indirect one. It helps decide which employers become certified in the H-1B program, the employer then decides who gets the visas, and those visa holders, in turn, decide whom they will marry.
Two of the six programs have annual numeric ceilings for first-time admissions, 66,000 for H-2B and 85,000 for H-1A, the others do not, except for a small sub-category of H-3, that of Special Education Exchange Visitors, who are to be trained to educate children with disabilities. There can be no more than 50 of these visas issued each year. (I do not know if this program is actually used.)