Root cause it. The USA does not have an illegal immigration problem. It has a "huge, slow immigration bureaucracy" problem that makes the legal path so slow and difficult that people are incentivized to gamble on illegal paths.
Having a difficult and selective immigration process that rejects the vast majority of applicants is not a problem. It is exactly how an immigration system should work. We want the best.
There exist a large number of legal pathways to permanent residency in the US, some of which do take unreasonably long; employment-based green card applications for Indian nationals famously have a decade-long waiting period. They should be reformed and improved.
But a big part of the problem is that many people do not have a legal pathway available to them, and either don't believe that or don't wish to accept it. So they spend years carefully pursuing every bit of due process they're entitled to, and those stories become part of the "slow immigration bureaucracy", regardless of whether the result was ever really in question. This is where immigration reform proposals have generally gotten bogged down; some people strongly feel we should resolve this by creating a general legal pathway, others feel we should resolve it by expediting removals, and both groups are very hesitant to agree to a proposal that doesn't resolve it at all.
Not even this. The USA has a labor shortage that is filled by workers who used to migrate seasonally until it was no longer allowed, thus creating a perverse system that encouraged business owners to look the other way and immigrants to stay instead of leave.
A long time ago, the southwestern part of the USA was Mexico, but a certain destiny manifested itself and changed that. It seems like this didn't affect day-to-day life due to a generous treaty for a while until some Americans decided they deserved the land there more than the people who were there.
https://en.wikipedia.org/wiki/Mexican_Repatriation#Cession_o... -- see the part about 1930 removals.
Obviously, the people who were kicked out were performing some useful economic function, so the USA decided to have it both ways: The Bracero program. https://en.wikipedia.org/wiki/Bracero_Program
This program of importing cheap labor had an expiration date, and it was allowed to expire in the 60s. Guess what happened then?
https://pmc.ncbi.nlm.nih.gov/articles/PMC9017686/
> Despite the forced removal of Mexicans during the 1930s, as soon as the United States entered the Second World War, authorities approached Mexico to negotiate a binational treaty that arranged for the annual entry of legal workers for seasonal labor in U.S. agriculture (Galarza 1964; Calavita 1992). The resulting Bracero Program lasted from 1942 through 1964, and its effect on the likelihood of migration is readily apparent in Figure 3. Between 1940 and 1945 the probability of U.S. migration rose nearly seven times, going from 0.003 to 0.020 before leveling off briefly and then rising to new plateau of 0.029 from 1956 to 1959. In 1960 Congress began to phase out the Bracero Program, finally letting it expire at the end of 1964, bringing the probability of migration down to 0.017.
Why did they let it expire? presumably to increase demand for American labor. A laudable goal to be sure, but is that really what happened? Surely people stopped crossing the border to do labor here and Americans started getting hired more.
This whole thing is beyond messed up and the fact that this history is essentially erased (I wasn't taught this in school) absolutely boils my blood.