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 pacification of the Iroquois enabled a post-Revolutionary war resumption of westward migration. The Trading Post soon became a tavern and Inn, and was soon receiving emigrants heading west as it was located above the cut bank overlooking first ford that could be reached to those descending from the Mountains Brownsville is located 40 miles south of Pittsburgh along the east bank of the Monongahela River, and until the 1850s steel boom—because it sat atop the first water routes west—eclipsed Pittsburgh in importance, size and population.According to the United States Census Bureau, the borough of Brownsville, located as a county border town has a total area of 1.1 square miles, of which 0.97 square miles is land and 0.1 square miles, or 10.