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 (64 km) south of Pittsburgh along the east bank of the Monongahela River.
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 (2.8 km2), of which 0.97 square miles (2.5 km2) is land and 0.1 square miles (0.3 km2), 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 opposite shore West Brownsville in Washington County. As a community, the town is the central population center for a number of outlying hamlets geographically tied to the town for the same reasons they were founded nearby—Western Pennsylvania has far more hills and steep slopes than flats or gentle sloping terrains suitable for settlement. This keeps Brownsville at the nexus of the transportation infrastructure which grew up during its history. While no longer a passenger depot, the town and cross-River West Brownsville share an important Railway bridge creating a balloon loop allowing the turning of complete coal trains. Newest is the limited access toll road PA Route 43, which connects the town to strategic points and southern Pittsburgh at Clairton. River hugging PA Route 88, connects to towns up and down the Mon Valley and the historic National Road (now US Route 40) reached East Saint Louis, Illinois and connected the town to the immigrants arriving in the port of Baltimore traveling west on the Cumberland Turnpike and the National Road.
From its founding, well into the 19th century, as the first reachable population center west of the Alleghenies barrier range on the Mississippi watershed, the borough quickly grew into an industrial center, market town, transportation hub, outfitting center, and river boat-building powerhouse. It was a gateway destination for emigrants heading west to the Ohio Country when a trading post, and the new United States' Northwest Territory and their "legal successors" for travelers heading westwards on the various Emigrant Trails both to the Near West and later Far West from its founding until well into the 1850s.