Mustang Island State Park is a state park located south of the city of Port Aransas, Texas, United States on the coast of the Gulf of Mexico that covers 3,954 acres and has a 5-mile beachfront. The land was acquired from private owners in 1972 and opened to the public in 1979. The island takes its name from wild mustangs that roamed the island which eventually succumbed to ranching in the late 1800s.