Aransas Pass is the water passage between Mustang and St. Joseph islands, located at 27°50' north latitude and 97°03' west longitude. A deepwater entrance has been dredged into channels leading to Corpus Christi, Aransas, and Red Fish bays. This natural pass over a sandy bar was known to exist as early as 1528, when it was clearly indicated on the Bratton map. It was called Aránzazu by Governor Prudencio de Orobio y Basterra on his map of 1739; the name was altered to Aransas on the map of a Captain Monroe of the ship Amos Wright (1833). Powers and Hewetson colonists came into Copano Bay across the Aransas bar in 1830–34, when the water depth was variously reported to be seven to eighteen feet.
The commercial need for a deepwater entrance and port south of Galveston focused serious attention on the Aransas bar as early as 1853, when considerable material was being lightered to the mainland for trade with settlers and Mexico. By 1854 the Texas legislature had authorized a seven-mile channel from Corpus Christi to the bar. In 1855 a lighthouse was erected on Harbor Island in Red Fish Bay adjacent to the pass (see ARANSAS PASS LIGHT STATION), but the lighthouse was soon more than a mile away, since the pass migrated toward the south. In the years following, the construction of dikes, revetments, sand fences, jetties, brush and stone mattresses, and tree plantings all failed to stop the erosion or to deepen the channel across the bar significantly.
By 1885 jetties, a breakwater, and a mattress revetment along the channel face of Mustang Island had greatly retarded the erosion. A south jetty, known as the Mansfield Jetty, was also constructed of brush mattresses and stone. By 1889 an eighteen-inch-thick riprap cover, which effectively curtailed the erosion, had been installed. A government decision to develop Galveston as the Texas deepwater port temporarily prevented appropriations for further major changes.
In 1890 the Aransas Pass and Harbor Company, under government contract, began a major effort to deepen the channel through the pass. The company was to construct two jetties. The south or Nelson jetty was constructed of cylindrical wooden caissons that extended 1,800 feet eastward along the face of the Mustang Island channel. The north, or Haupt, jetty was constructed of stone. It was detached from the shore of St. Joseph Island and curved; it was intended to be 6,200 feet long but was completed only to about three-fourths of its planned length. These jetties failed to increase the channel depth. A subsequent attempt, by a contractor of the company, to blast a channel with thousands of pounds of dynamite was also unsuccessful.
The Rivers and Harbors Act of 1899 provided for the removal of the old Mansfield jetty. After two serious attempts and much difficulty the work was considered complete by 1911. Authorization was given to construct a new south jetty and to join the detached Haupt jetty to St. Joseph Island in 1907. By 1919 the south jetty had been completed to 7,385 feet and the Haupt jetty to 9,241 feet, and the channel began to deepen. With the assurance of deep water across the bar, channels were opened to Aransas Pass, Rockport, and Corpus Christi. The great hurricanes of 1916 and 1919, with related economic alterations, caused the United States Army Corps of Engineers to declare Corpus Christi the South Texas deepwater port after access to the city was made available through Aransas Pass. The port of Corpus Christi opened in 1926 and has continued to grow and to accommodate larger and deeper-draft vessels.