Jim Crow Laws
From dKosopedia
Jim Crow laws mandated de jure segregation and other anti-Black measures in the former Confederacy and a few other areas, including Washington DC, starting in 1876. The practice was extended to the US military until forbidden by President Harry Truman. The Supreme Court gave Jim Crow its judicial blessing in Plessy v. Ferguson in 1896, under the theory known as "Separate But Equal". The Earl Warren Supreme Court began the process of overturning the Jim Crow laws in Brown v. Board of Education, explicitly ruling that separate is inherently unequal. The remaining segregation laws were explicitly outlawed in a series of Civil Rights Acts and the Voting Rights Act.
The origin of the name is obscure. It is conjectured to be the name of a real person, or made up name based on a somewhat complicated pun: the use of a crowbar (crow) as a jimmy (jim), together with the pejorative "crow" (black bird) for Black person, and Jimmy, a name for a crow in this sense.