Charles Mingus, Sr. was among those in the U.S. Army who were Buffalo Soldiers (when the Army was racially segregated). There are two cities called Nogales -- one in Arizona, and the other right across the border in Mexico. There were a number of border skirmishes during the Mexican Revolution (1910-1920), and it would be interesting to find out what role Charles Mingus, Sr. had in the Army during this time.
It is fascinating to think that Charles Mingus, Sr. was stationed in Richmond, VA in the late 1890s. Interesting geographical coincidence, given that MAP concerts have been happening in Richmond since 2007.
The theme of borders and interstices seems to be a key part of Charles Mingus, Jr.'s life and work -- the fact that he was biracial, that he developed music that drew on intersections among various influences and genres (e.g. blues, jazz, western classical), that he worked among borders between traditional and experimental forms, and more. Discussions about the U.S.-Mexico border continue to be polarizing and politically charged, and politics is something that Mingus never backed away from, in his life and music. Having been born in the borderlands (frontera Estados Unidos–México) must've had a big influence on him. As his son Eric Mingus said in an interview with the journalist John Washington, "That was what he was all about, the bleeding of cultures."