Donora is a borough in Washington County, Pennsylvania, 20 miles (32 km) south of Pittsburgh on the Monongahela river. Donora was incorporated in 1901. Donora got its name from a combination of William Donner and Nora Mellon, banker Andrew W. Mellon's wife. Agriculture, coal-mining, steel-making, wire-making, and other industries were conducted in Donora early in its history. In 1910, 8,174 people lived there; in 1920, 14,131; and in 1940, 13,180 people lived in Donora. The population was 5,653 at the 2000 census. Donora is a Rust Belt place which has lost most of its industrial capacity. It is in the "Mon valley" 5 miles (8.0 km) downriver from Charleroi and 25 miles (40 km) upstream of Braddock, Pennsylvania.
In 1794, 1 mile (1.6 km) east of Donora, the Whiskey Insurrectionists held several meetings at Fells Church.
A trolley line opened in Donora on December 15, 1901, linking First and McKean and Fifteenth Street and Meldon. It was extended in 1911 to Black Diamond to connect to the Charleroi to Pittsburgh interurban trolley. The line was abandoned on May 5, 1953.