The Brownsville affair, or the Brownsville raid, was an incident of racial discrimination that occurred in 1906 in the Southwestern United States due to resentment by white residents of Brownsville, Texas, of the Buffalo Soldiers, black soldiers in a segregated unit stationed at nearby Fort Brown. When a white bartender was killed and a white police officer wounded by gunshots one night, townspeople accused the members of the African-American 25th Infantry Regiment. Although their commanders said the soldiers had been in the barracks all night, evidence was allegedly planted against the men.

Brownsville is a city in the U.S. state of Texas and the seat of Cameron County, located on the western Gulf Coast in South Texas, adjacent to the border with Matamoros, Tamaulipas, Mexico. The city covers 145.2 sq mi (376.066 km2), and had a population of 186,738 at the 2020 census. As of the 2020 U.S. Census, it is the 139th-largest city in the United States and 18th-largest in Texas. It is part of the Matamoros–Brownsville metropolitan area. The city is known for its year-round subtropical climate, deep-water seaport, and Hispanic culture.