In the American Southwest, much of the construction and landscaping work, especially odd jobs, is done by immigrants, usually from Latin America.

Historically, construction has been seen as a union job, and that's probably still true in certain parts of the U.S. and in certain specializations.

As far as housing arrangements, I'm not positive, but I do believe immigrants tend to pack in more people per square foot of an apartment. I have not heard of dorm-style arrangements run by employers.