The Bracero (translated by Google to "laborer") program, a series of laws and policies that lasted from the late 1940s to the early 1960s, by which Mexicans were allowed to come to the US on temporary work permits, is sometimes mentioned in discussions about immigration. It didn't grant many rights to the Mexican workers. They couldn't stay and couldn't become citizens, and they were sometimes not paid what they had coming, and sometimes they even went on strike. The program, which brought around five million Mexicans here to work over its 22 years, has a legendary status among some on the Left, who usually talk about immigration from a macro economic or a Marxist viewpoint, namely in terms of how immigration policy has fluctuated back and forth according to the needs of Capital for labor.
As with much of government policy, it's often difficult for the layman, let alone an experienced journalist, to see and to demonstrate direct lines between the wants and needs of Capitalists and what gets enacted as legislation, but that's where good academic work is so valuable and insightful, and that kind of work exists on the Bracero program and on immigration policy as it relates to other nationalities and over time. A lot of the back and forth between the rich and the politicians goes on behind closed doors, at fancy restaurants, or indirectly; maybe a Jaimie Dimon will write an op-ed for the Wall Street Journal that lays out in somewhat coded language what he and his class expect from their politicians, then a few weeks later another CEO will publish something in an obscure journal that mainly insiders read, etc. If you're not paying attention with a trained eye it all flows under the radar, but a diligent researcher can go back and show how immigration policy has changed as the needs of the economy for labor changed.
I somehow came across these photos and several others on the Department of Homeland Security web site, where this page has links to more photos and a lot of other information; historical, genealogical (some free, some for a fee), webinars, etc.
As you can see in the upper right of this screen shot I took that there's also one of those links you can click on to talk to someone. You can ask Emma.