Trafford is a borough in Allegheny and Westmoreland counties in the U.S. state of Pennsylvania. Located near Pittsburgh in western Pennsylvania, the borough lies primarily in Westmoreland County; only a small portion extends into Allegheny County. It was incorporated in 1904 from the northernmost corner of North Huntingdon Township, and was named by George Westinghouse for Trafford near Manchester, England. Westinghouse purchased the land in 1902, and the Trafford Foundry began operations on October 3, 1903. The population was 3,174 at the 2010 census. Of this, 3,113 were in Westmoreland County, and only 61 were in Allegheny County.
Trafford is located at 40°23′2″N 79°45′32″W (40.383860, -79.758919).
According to the United States Census Bureau, the borough has a total area of 1.4 square miles (3.7 km²), all land.
Trafford has four borders, including Penn Township to the northeast, North Huntingdon from the east-northeast to the south, and the Allegheny County neighborhoods of North Versailles Township to the west and Monroeville to the north.
As of the census of 2000, there were 3,236 people, 1,526 households, and 900 families living in the borough. The population density was 2,258.6 people per square mile (873.7/km²).