Brownsville is a borough in Fayette County, Pennsylvania, United States, first settled in 1785 as the site of a trading post a few years after the defeat of the Iroquois enabled a resumption of westward migration after the Revolutionary War. The trading post soon became a tavern and inn and was receiving emigrants heading west, as it was located above the cut bank overlooking the first ford that could be reached to those descending from the Allegheny Mountains. Brownsville is located south of Pittsburgh along the east bank of the Monongahela River.
According to the United States Census Bureau, the borough of Brownsville has a total area of , of which is land and , or 10.47%, is water—most of which is the Fayette County half of the Monongahela River between the community and the flatter lands of West Brownsville on the opposite shore in Washington County. As a community, the town is the central population center for a number of outlying hamlets geograph