The Flight 93 National Memorial is a memorial built to commemorate the crash of United Airlines Flight 93, which was one of four aircraft hijacked during the September 11 attacks in 2001. The memorial is located in Somerset County, Pennsylvania, with the vast majority in Stonycreek Township, and with a small portion in Shade Township. It is 78 miles (126 km) southeast of Pittsburgh and 226 miles (364 km) west of Philadelphia.

United Airlines Flight 93 was a domestic scheduled passenger flight that was hijacked by four al-Qaeda terrorists on the morning of September 11, 2001, as part of the September 11 attacks. The hijackers planned to crash the plane into a federal government building in the national capital of Washington, D.C. The mission became a partial failure when the passengers fought back, forcing the terrorists to crash the plane in Somerset County, Pennsylvania, preventing them from reaching al-Qaeda's intended target, but killing everyone aboard the flight. The airliner involved, a Boeing 757-222 with 44 passengers and crew, was flying United Airlines' daily scheduled morning flight from Newark International Airport in New Jersey to San Francisco International Airport in California, making it the only plane hijacked that day not to be a Los Angeles–bound flight.