>>50724357230 years ago.
Most came after Ronald Reagan gave amnesty to the 2.7 million or so illegals, many of whom were not even in the nation until they learned of the upcoming amnesty and rushed in to claim to have been in the USA for years.
This told everyone that if you come as an illegal and make it for awhile eventualy you get everything you wanted.
Information took longer pre internet, but by the early 1990s it had become clear nobody was reversing it and illegaly going to the United States was the easiest way to get a better life.
The state most went to was California, which had immigrant communities and you could speak spanish and readily find work.
Californians noticed this, that they were being replaced by an invasion, the federal government under both parties was failing to secure the border while claiming jurisdiction over the matter, and basicly assisting with the replacement of California.
Prop 187 was passed to fix the issue, overwhelmingly supported in most of the state except around the influence of the gays and hippies of San Francisco.
One of the strongest provisions included punishing employers of illegals, removing the ability of illegals to get income and removing the incentive to be an illegal.
Then a federal jewish judge, from the federal government failing to secure the border and assisting in the replacement of California, just single handidly undid the will of the entire state and trashed the proposition.
By the 2010s the descendants of these illegals outnumbered the former California population and their descendants and the free college, free healthcare, free food assistance, etc for illegals paid by tax payers started to be rolled out.
The federal government gave California away to foriegners against the will of Californians.
Until who they gave it away to outnumbered the former population and supported it.
Then California became the gateway through which they spread across the nation.