Gap is a census-designated place and unincorporated community in Salisbury Township, Lancaster County, Pennsylvania, United States, with a ZIP code of 17527. The population was 1,931 at the 2010 census. U.S. Route 30 passes through the town, which is also the terminus for four Pennsylvania highways: 772, 741, 897, and the heavily used 41, which leads toward Wilmington, Delaware. Gap lies approximately 16 miles east of Lancaster and 49 miles west of Philadelphia.