Brownsville is a small unincorporated community and census-designated place in Washington County, Maryland, United States, near Gapland in an area known as Pleasant Valley. Its population was 89 as of the 2010 census.Tobias Brown, son of Rudolph Brown, was one of the first settlers of Washington County, and owned a tract of farmland extending from Gapland, south to the future location of Brownsville. John Brown, son of Tobias, and his son Cornelius established a tannery in the swamp land at the head of a small tributary to Israel Creek, and built a home on the east side of the valley overlooking the tannery. The town was named for the family. The first post office in Brownsville was established January 28, 1833, with John H. Beall as postmaster. He was succeeded on February 3, 1836, by John Brown, who was born near Brownsville, December 20, 1790, served as a soldier in the War of 1812 and saw action at the Battle of North Point.