Apparently your knowledge of history is fairly poor. Start here and then we can talk.
Mariel boatlift - Wikipedia
Some were truly dissidents. Some were truly free thinkers seeking opportunity. Some were mental patients. Some were criminals. Most were uneducated and unskilled. The wages for unskilled labor were 20% lower than the national average because of a ready supply of labor.
That isn't racism. That is established historical fact. What makes you think the people pouring across the border today are any better educated or less criminal?
Those people weren't pouring across the country. They came here in boats and Castro used that flight to freedom to empty his prisons and mental health facilities.
The Mythical Connection Between Immigrants and Crime
They might start by pointing out that numerous studies going back more than a century have shown that immigrants—regardless of nationality or legal status—are less likely than the native population to commit violent crimes or to be incarcerated. A new
report from the Immigration Policy Center notes that while the illegal immigrant population in the U.S. more than tripled between 1990 and 2013 to more than 11.2 million, “FBI data indicate that the violent crime rate declined 48%—which included falling rates of aggravated assault, robbery, rape, and murder. Likewise, the property crime rate fell 41%, including declining rates of motor vehicle theft, larceny/robbery, and burglary.”
