Matagorda Island is a sand barrier island averaging two miles wide and about fifty miles long in Calhoun County (at 28°14' N, 96°38' W); Cavallo Pass separates the island from Matagorda Peninsula. Matagorda Island separates Espíritu Santo Bay and San Antonio Bay from the Gulf of Mexico and is intermittently separated from St. Joseph (San José) Island by Cedar Bayou, a sometimes open, sometimes closed water passage that was intentionally plugged in 1979 to protect Mesquite Bay from contamination after an oil spill. It was partially reopened by Hurricane Allen in 1980 (see HURRICANES) and further cleared by dredging in 1988.
Matagorda Island was probably first seen by a European in 1519 when Alonso Álvarez de Pineda sailed along the Texas coast and provided the first known map of that coast. There appears to have been no settlement on the island until the government of Texas authorized the town of Calhoun to be laid out on the northeast corner of the island in 1839; a customhouse was established there. The town did not thrive, however, and the customhouse was moved to Galveston Island in 1844. The town of Saluria was laid out in 1847 on the northwest corner of Matagorda Island, and the government also built a lighthouse there. Saluria appears to have been thriving at the beginning of the Civil War. In 1862 Fort Esperanza was constructed to protect Pass Cavallo from entry by Union forces. The town and the fort were abandoned by Confederate forces in November 1863 and occupied by the federals, who withdrew in June 1864. Fort Esperanza was never reoccupied. Saluria and the remains of Fort Esperanza were destroyed by the storms of 1875. The town was partially rebuilt and then totally destroyed by the storm of 1886. It was never rebuilt. In 1943 a bombing and gunnery range was constructed on the north end of the island; it was deactivated after World War II and reactivated for the Strategic Air Command from 1949 until 1975.
An 11,502-acre tract on the south end of the island was controlled by the Wynne Ranch from about 1925 until 1986, when the state and the federal governments reached an agreement to establish a national wildlife refuge on the entire island. In spite of the location, which is accessible by boat or air only, the refuge hosts about 10,000 visitors a year.