The John Heinz National Wildlife Refuge at Tinicum is a 1000-acre (4.05 km2) National Wildlife Refuge in Philadelphia and Tinicum Township, Delaware County, in Pennsylvania. Adjacent to the Philadelphia International Airport, the refuge serves to protect the largest remaining freshwater tidal marsh in Pennsylvania. Established in 1972 as the Tinicum National Environmental Center, it was renamed in 1991 after the late H. John Heinz III who had helped preserve Tinicum Marsh.