Port O’Connor, on State Highway 185 and Matagorda Bay in southern Calhoun County, was laid out in 1909 by the Calhoun Cattle Company on the 70,000-acre Alligator Head Ranch formerly owned by Thomas M. O’Connor. By 1911 the International-Great Northern Railroad had reached the community, which was named for O’Connor. By 1914 the town had become the summer resort terminus of the St. Louis, Brownsville and Mexico Railway, with a hotel, a bathing and dance pavilion for tourists, and a population of 350.
That year the community also had three general stores, two churches, two fish and oyster plants, a bank, an ice plant, and a lumber company. At that time farmers in the area raised figs and citrus fruit and shipped their product to the town’s Fig Orchards Company for processing.

Port O’Connor grew from a population of 300 in the 1930s to 600 by the 1940s; during that period the number of businesses varied from eight to fifteen. The 1936 county highway map showed three churches and a school at the townsite. In 1939 the Gulf Intracoastal Waterway reached the community, linking New Orleans with Corpus Christi. Hurricanes in 1919, 1942, and 1945 damaged the town, but Hurricane Carla in 1961, which came ashore at Port O’Connor, leveled it, destroying the five-block downtown area.
Growth resumed after the disaster, however, because of the community’s proximity to Matagorda Air Force Base. The town’s population reached 1,010 in 1969.

From 1975 to 1988 it was reported as 810. The number of businesses reached a high of twenty-seven in 1981.
In the late 1980s the town was a fishing, tourist, and retirement center, and in 1990 it reported a population of 1,184 and twenty-two businesses.

The population remained the same in 2000, however, the number of businesses had increased to sixty-eight.