Brownsville, Pennsylvania, was first settled in 1785 as the site of a trading post a few years after the defeat of the Iroquois. The trading post soon became a tavern and inn and received emigrants heading west, and developed into an industrialized community and transportation hub. Its population peaked at 8,000 in 1940 and began to decline because of post-World War II suburban development on its fringes and a restructuring of the railroad and steel industries that caused a severe loss of jobs. The borough had a population of just over 2,100 in 2020.
Clairton, Pennsylvania, was incorporated on April 12, 1903, and was centered around Clairton Works, the largest coke manufacturing facility in the United States. The production of coke was vital for the pig iron blast furnaces that produced steel throughout the region. The population of Clairton peaked at nearly 20,000 residents in the 1950s, but a catastrophic collapse of the domestic steel industry caused the town to be declared economically stressed in 1988.
McKeesport, Pennsylvania, established in 1795, remained a small village until 1830, when coal mining began in the region. The town peaked at 55,000 residents in 1940 during a time when National Tube Works dominated the local industry. The decline and eventual closure of National Tube and other steel plants in the area, along with a massive fire that destroyed a significant portion of downtown in 1976, led to McKeesport’s population collapsing to under 20,000 by 2010.