Leechburg is a borough in southern Armstrong County in the U.S. state of Pennsylvania, 35 miles (56 km) northeast of Pittsburgh. As of the 2010 census it had a population of 2,156. Leechburg was founded by David Leech, for whom it was later named, and was incorporated as a borough in 1850.
Located along the Kiskiminetas River, Leechburg was a major port of the Pennsylvania Canal. Early in the 20th century, it was the site of extensive steel sheet works, foundries, cement plants, and productive coal mines. Leechburg was the first place where natural gas was used for industrial purposes.