Brownsville is a city in Cameron County, Texas. As of the 2000 census, the city population was 139,722. It is the county seat of Cameron County. Brownsville is located at (25°55′49″N97°29′4″W) (25.930307, -97.484424), on the U.S.-Mexico border (marked here by the Rio Grande or Río Bravo del Norte) from Matamoros, Tamaulipas.