The area that is now San Patricio County has been inhabited by indigenous people (the Karankawa) for more than 6,000 years, a tribute to its key location. Modern settlement of the area began in 1828, however, when a group of Irish families led by John McMullen and James McGloin contracted with the Mexican government to settle around 360,000+ acres of land north of the Nueces River. Further Scotch-Irish settlement in the area led to the establishment of the area's first town, San Patricio de Hibernia. In 1834, the Municipality of San Patricio was established, under the Mexican state ofCoahuila y Tejas. It is this name, that of Saint Patrick, patron saint of Ireland, that would be adopted by the community to this day.
The county was thrown into disarray only a year later in 1835, when the Texas Revolution broke out nearby at the Battle of Goliad. It was San Patricio colonists who led the next attack of the Revolution, taking control of Fort Lipantitlan, south of present-day Mathis. Soon thereafter, the local Texan detachment was nearly wiped out by Mexican forces, and the colonists relocated to present-day Victoria. Most of the original settlers did not return, but when Texas won its independence, the area was established as San Patricio County.
Peace was not established in the area until 1845, when Gen. Zachary Taylor established an army encampment at present-day Rockport, just as Texas became the 28th state of the United States at the end of that year. That peace was short-lived, however, as the Mexican-American War began a year later in 1846. The end of the war in 1848 allowed for real settlement in the area to take place.
The U.S. Census reported only 200 permanent residents (3 of whom were slaves) in 1850, with ranching and cattle farming the area's primary industry. New settlers would soon arrive in South Texas, establishing its first permanent settlements throughout the 1850's. Crop cultivation developed slowly in the area, however, with cattle farming remaining prevalent. The first community in present-day Ingleside was established around 1854.
The Civil War once again brought conflict to the area, forcing many of the local residents to once again leave their homes (to Goliad) during the war. The county was not on the front lines of the war, but was key to the "cotton road," a smuggling route used by the Confederacy to trade with Mexico. A Confederate fort was established at present-day Aransas Pass to combat union ships in the Gulf of Mexico, which meant that raids occasionally hit the Corpus Christi Bay area, including San Patricio. Ingleside, which sits on the coast of the Bay, was frequently attacked, forcing its residents to relocate.
Following the Civil War, the county saw an increase in its population as Southerners flocked to the area for its cheap land. By 1870, the area had staple crop production alongside an extensive cattle industry. It truly began to prosper financially in 1885, with the construction of the San Antonio & Aransas Pass Railway allowing for cattle and crop transport out of the area. The towns of Mathis, Sinton and Gregory were established by 1890 along the railroad. Taft would be established soon thereafter by a former newspaper editor, Charles P. Taft.
The County continued to prosper as thousands of European immigrants moved to the area after the turn of the 20th century. The early 1900's saw new farming and cattle establishments alongside the new towns of Odem, St. Paul, Edroy and Sodville which were built along the railroad.
By 1920, there were 11,386 permanent county residents, with 757 operating farms. Farming had overtaken the local industry, with cotton becoming the county's most important cash crop. Some 60,000 acres of cotton were planted in 1920, with 155,000 acres by 1930.
Later in the 20's, the oil and gas industry discovered the area, building several new pipelines in the county and establishing a major site at Welder Ranch in 1935. The East White Point Field, south of Taft, would be discovered soon thereafter, bringing the oil rush to the area. More industries would follow, especially in Ingleside, where then-established factory sites still remain. Many of the oil and gas fields that prospered during this era have since returned to agricultural use at present.
Modern San Patricio is home to a combined economy of energy, chemical and maritime industries; alongside agriculture, mariculture, tourism and industrial manufacturing. The area's rich farmland remains in active use, but today's San Patricio horizon looks a bit different, as the county is now home to the Papalote Creek Wind Farm (sited primarily on San Patricio farmland).