Mustang Island is an eighteen-mile-long barrier island between Corpus Christi and the Gulf of Mexico, south of St. Joseph's Island and connected to Padre Island on the south (its center is at 27°44' N, 97°08' W). In the past the island has been cut by Newport Pass and Corpus Christi Pass. Both are now sanded over. Aransas Pass runs between Mustang Island and St. Joseph's Island and provides access for deep-draft vessels to Corpus Christi Bay and the city port, to the United States Navy Battleship Group Homeport, and to the Gulf Intracoastal Waterway. That pass through the barrier islands is protected by jetties extending into the Gulf from both St. Joseph's and Mustang islands.
Capt. Robert Mercer brought the first family to Mustang Island and built the first house there at what he called El Mar Rancho in 1853. Mrs. Mercer is reputed to have been the first white woman in the area. Herds of mustangs roamed the island when Mercer arrived. A quarantine station was established at the north end in 1879 and later moved across Lydia Ann Channel to Harbor Island. The first life-saving station in the area was established on the north end in 1880. A two-story structure was constructed in the early 1880s to house workers for the Mansfield Jetty (the south jetty for Aransas Pass). After work was stopped, the structure was converted into a hotel and is today the Tarpon Inn, a landmark. Elihu Ropes, a developer, attempted to cut a channel across Mustang Island in 1889–91. A small town named Ropesville developed, later called Tarpon. On April 1, 1911, its name was changed to Port Aransas. Port Aransas, on the north end of Mustang Island, is connected to the mainland by the State Highway 361 causeway and a state-operated free ferry. Park Road 53 runs south down the island and is connected at the south end, by a causeway across the Laguna Madre, to Flour Bluff on the mainland. Mustang Island State Park, established in 1972 on the lower end of the island, offers more than five miles of beach front. The annual Deep Sea Roundup in July is among the largest and oldest fishing tournaments on the coast.