The south was flooded with cheap foreign labor displacing blacks etc into the labor pool. At the same time, politicians were adding people to welfare etc. So, many groups look to crime and drugs for a way out. Very much planned.
Last I checked, the % of foreign born residents in the US now (15.8%) is about the same as it was in 1915. The difference is that the latter was not incentivized by welfare, but to work, coming from a culture of work, but while most immigrants to the US do want to work - less foreign born are on welfare than among native-born Americans - yet both classes are incentivized to obtain welfare. The gov. itself has spend millions promoting SNAP. 42 million Americans are enrolled.