A pivotal moment in The Great Strike happened here, on July 21st, 1877. Striking railroad workers blocked the tracks, while their families and supporters looked on from the hillside. Militiamen were brought in from Philadelphia to clear the workers from the tracks and restore train service. At about 5pm, they fixed bayonets and charged the unmoving crowd, which fought back by throwing stones. The troops subsequently opened fire on the striking workmen, and turned their guns on women and children watching from the hillside. Twenty people were killed, including at least 3 children.

The use of state troops to assault citizens outraged the general population of Pittsburgh. A furious mob forced the Philadelphia troops out of the city. For two days after the massacre, Pittsburghers set out to loot and burn every piece of Pennsylvania Railroad property between this point and Downtown.