American Jobs For Real Americans:
The 1930's President Herbert Hoover campaign slogan that inspired the deportation of nearly 2 million hispanics in 1931 alone (almost 2% of the US population), for exacerbating the overall economic downturn of the Great Depression, a push to free up employment for Whites; a slogan that implied that only Whites could be real Americans.
One famous of deportation being the Californian 1931 "La Placita" raid, which 400 hispanics were rounded in a Los Angeles park, thrown in vans and dumped over the Mexican border.
Raids like this occured all over the country, particularly with the INS (Immigration and Naturalization Service) agency (original ICE), which simply deported if you looked hispanic, resulting in 60% of the deportees being US citizens exiled in Mexico.
While many cases like the above occured under the direction of city, county and state authorities in huge numbers, most of the 2 million deportees were self-deportations.
Why did they self-deport so rapidly? A series of legislative reforms ("American Jobs For Real Americans!") that required US citizenship to be employed in the US (spoiler: they checked skin not passports), denied all visa applications from Meso-America, withheld unemployment relief from hispanics, and most major manufacturers just blanket fired all hispanic workers (citizen or not).
The point is simple, the United States could get rid of all hispanics with relative ease: US citizenship employment requirement, US citizenship social-benefit requirement, US citizenship healthcare requirement, and revoke US citizenship from all non-whites.
Wouldn't even need to have immigration enforcement agencies, they would literally all leave, as they wouldn't be capable of living in the US.
The United States could end the migration crisis Mexican invasion today... if they wanted to.