Harbor Island is in Red Fish Bay opposite the city of Aransas Pass (at 27°52' N, 97°05' W). The island straddles the Nueces-Aransas county line and is accessible from the mainland by State Highway 361. In 1720 the French explorer Jean Béranger discovered Aransas Pass and landed on what is now known as Harbor Island to place an armorial marker in the sand. In 1857 the pass had become important enough to rate a lighthouse, which was built on Harbor Island, since at that time the island was squarely in front of the channel to the Gulf of Mexico. In 1912 the United States Army Corps of Engineers finished deepening Aransas Pass and dredged a deepwater port at Harbor Island. Oceangoing vessels began calling regularly and in celebration a week-long gala was held in September of 1912. The 9.6-mile Aransas Harbor Terminal Railroad connected Harbor Island with the mainland and the San Antonio and Aransas Pass Railway. A cotton compress was built on the island in 1913, and during World War I a concrete shipbuilding firm was constructed there. By 1927 the Humble Oil and Refining Company (later Exxon Company, U.S.A.) had built a large oil terminal on Harbor Island. Other major oil companies laid pipelines to the docks to meet the oil tankers. With the opening of a deepwater port in Corpus Christi in 1926, the dry cargo at Harbor Island dried up entirely. In the late 1980s an oil terminal still operated there, but all of the old cargo docks were gone. Brown and Root ran an oceangoing oil-rig construction company on the island. A number of state-operated ferries regularly took large numbers of cars from Harbor Island to Port Aransas and Mustang Island.