That is a larger issue with many false paths. The fault lies in the economic system, not in issues of immigration. It is just easier for some people to blame immigrants/visible minorities for their plight.
In the case of
black vs. Mexican immigrants (particularly in the American Southwest), the conflict dates back to the pre-WWII era, where innumerable Mexicans would consciously move into more affordable (read: cheap) neighborhoods, and often being illegal, would take jobs from black employees who were seasoned in
trying to fight for their rights through protest, unions (if the unions were typically screwing them over) and other means, which angered employers looking to pay a penny for labor worth dollars. Knowing how they (Mexican immigrants) were displacing black workers, but frankly not caring, you had generations of blacks (who correctly felt they were--once again--booted from a place they earned (but wanted to rise above) as a major part of the people who truly built America.
This conflict was often linked to violence between the groups, especially during the late Civil Rights movement era, where the historic fight / gains that changed a nation (and influenced other countries) were being piggybacked by Mexican immigration advocates (like the astoundingly racist Council of La Raza), who in turn, would drive them from once-traditionally black towns, overwhelming districts (with endless illegal immigrants), elections to influence officials to purposely supplant blacks in an official manner, and the take possession of gains / programs they fought and died for in favor of Mexicans and Mexicans
alone.
This problem exists to this day, with black activists laying out the current issues supported by history, but you won't hear that from certain people who are quick to hit "repeat" on what they see as a single cause: the "Eeevilll white corporations" as if they were puppeteering
all events in this regard, which is as far from the truth of history (part of which I experienced in California and later covered) as Little Red Riding Hood.
A long-lived state of hostility exists between blacks and Mexicans, and much of it comes from racist perceptions
born in Mexico, so conflict and displacing black people was an agenda, not happenstance, but certain people (not meaning you, theenglish) still preach the same, tired political lines used during every election cycle.