Canonsburg is a borough in Washington County, Pennsylvania, 18 miles (29 km) southwest of Pittsburgh. Canonsburg was lai out by Colonel John Canon in 1789 and incorporated in 1802. It was the central point of the Whiskey Rebellion of 1794. The borough is in a rich coal district, and most of the town's work force once worked in local steel mills or coal mines. Canonsburg's population in 1910, including South Canonsburg, which was annexed in 1911, was 5,588; in 1920 it was 10,632; and in 1940 it was 12,599. The population was 8,607 at the 2000 census.