Marcus Hook is a borough in Delaware County, Pennsylvania, United States. The population peaked in the 1920s with 5,324 inhabitants. 2,314 inhabitants were counted at the recent 2000 census. Marcus Hook's current mayor is George A. McClure. The borough calls itself "The Cornerstone of Pennsylvania". The 2005 Film One Last Thing... was set and partially filmed in Marcus Hook.

Marcus Hook is located at [show location on an interactive map] 39°49′6″N 75°24′56″W / 39.81833°N 75.41556°W / 39.81833; -75.41556 (39.818212, -75.415561)[2].According to the United States Census Bureau, the borough has a total area of 1.6 square miles (4.2 km²), of which, 1.1 square miles (2.9 km²) of it is land and 0.5 square miles (1.3 km²) of it (30.86%) is water. The lowest point in the state of Pennsylvania is located on the Delaware River in Marcus Hook, where it flows out of Pennsylvania and into Delaware.