Eighty Four is a small census-designated place in Somerset, North Strabane and South Strabane Townships in Washington County, Pennsylvania, United States. It lies approximately 25 miles southwest of Pittsburgh and is in the Pittsburgh metropolitan area. As of the 2010 census the population was 657 residents.
Eighty Four is home to the 84 Lumber company's world headquarters and home of the first 84 Lumber store. Eighty Four is a part of the Canon-McMillan, Trinity, Ringgold, and Bentworth school districts. The Avalon Motor Inn in Eighty Four was featured in the 2002 film The Mothman Prophecies.