Folcroft, borough (1990 pop. 7,506), Delaware co., SE Pa., suburb 8 mi/12.9 km SW of downtown Philadelphia, on Darby Creek; 39°53'N 75°16'W. Mfg. (chemicals, costume jewelry, food, machinery, textile prods.). Philadelphia Internatl. Airport to SE. John Heinz Natl. Wildlife Refuge to SE. Inc. 1927.