Liberty, the county seat of Liberty County, is on State Highway 146 and U.S. Highway 90 in the south central part of the county. The site is in a major oil and gas production area served by the Southern Pacific Railroad. Liberty once stood at the head of navigation on the Trinity River. The town was founded near the sites of a Spanish settlement called Atascosito (established in 1756) and Champ d'Asile, a French colony established in 1818. The area was first occupied by American squatters as early as 1818, when it was still under Spanish law; settlers along the Atascosito Road, which crossed the Trinity three miles to the north, petitioned unsuccessfully to be included in Stephen F. Austin's colony. Subsequently, under Mexican law, land commissioner José Francisco Madero established an office in the settlement and on May 5, 1831, granted thirty-six land titles there, thus forming a new municipality, Villa de la Santísima Trinidad de la Libertad. Hugh B. Johnston was made alcalde. In this Anglo-American colonization period, according to some sources, the town shortened its name to Liberty, after Liberty, Mississippi, whence many of the early settlers had come. Anahuac military commander John Davis Bradburn attempted to dissolve the ayuntamiento in Liberty on December 10, 1831, but the municipality survived. It was represented at the Consultation in 1835 and granted a post office in 1836. Throughout the period Liberty served as a shipping point for plantations along the Trinity, for lumber operations, and for a variety of shipments from farmers. Sam Houston practiced law in the community from the 1830s to the 1850s. He maintained two plantation homes in Liberty County until his death. In the Texas Revolution, Andrew Briscoe's Liberty Volunteers, organized in 1835, fought at the siege of Bexar and the battle of Concepción, and it was to Liberty in February 1836 that one of William B. Travis's letters requesting reinforcements at the Alamo was delivered by Joseph Dunman. After San Jacinto, captured Mexican officers were held for a time in Liberty at William Hardin's homestead, afterwards known as Mexican Hill. There the prisoners received kind treatment from Harriet Paine, a slave of Hardin's who lived to be nearly 100 and contributed to the area's history and folklore.
Liberty became the county seat and was incorporated in 1837. At that time, the town was a trade center for surrounding plantations. The arrival of Creole immigrant families in 1845 increased the area population, but by 1840 only ten or twelve houses stood at the townsite. James Taylor White furnished most of the beef for Jones and Company, an English beef-packing business located at Liberty Landing. A trading post and warehouse served local residents. The town functioned as an important port, with steamship transportation of passengers, trade, and mail to and from Galveston and with access to stage routes and ferry service across the Trinity. A school was founded in 1838. The population numbered 200 in 1845. The town cemetery was marked off in 1848. In the 1850s, as the community expanded, additional industry developed around its gristmills, cattle shipping docks, and two sawmills. The Liberty Gazette was published as early as 1855. In that year the local Methodist congregation had more Black members than Whites; in 1858, of a population of 651, 189 were Black. The Liberty Female Seminary and Male and Female School opened in 1858, and an Ursuline convent academy for girls in 1859. Liberty expanded as a shipping point when the Texas and New Orleans Railroad reached it in 1858, and in 1860 a Market House was under construction at the site of the future Sam Houston Elementary School. The Liberty Invincibles were organized in 1861 for duty in the Civil War, and military leaders enlisted additional men from the community. The railroad suspended operations, but had resumed by 1875. The schools closed briefly during Reconstruction. Residents cooperated with the Freedmen's Bureau and organized no local Ku Klux Klan, though segregation perdured. Smallpox and yellow fever epidemics in 1866 and 1867 slowed recovery, and the population dropped to 497 by 1880, when the town reported four churches, three schools, and a hotel. Liberty was divided into three wards in 1883. The Liberty Observer was first published in 1870, the Star State was first published in 1875, and the Vindicator in 1887.
By 1900 the town comprised roughly seventy houses, many of which stood alone on their respective city blocks. Livestock roamed the streets legally. Many local houses were owned by or rented to African Americans. The East Texas Bee was first published at Liberty in 1902; the Liberty Daily Courier, Progressive Outlook, and Liberty County News followed. Oil discoveries in 1903 at the Batson-Old oilfield in neighboring Hardin County made Liberty, the nearest train stop, a boomtown. Three cotton gins, a gristmill, and a cigar factory were operating there around 1910. By 1907 the Trinity Valley and Northern Railway Company, built for use of the Dayton Lumber Company, served Dayton, located on the west side of the Trinity River and originally known as West Liberty. A major boost in the population came in 1925 with the development of the South Liberty oilfield. The area's leading crop in the 1920s was cotton. Efforts to make the Trinity navigable for steamers continued from 1852 to 1940, when 236 miles of waterway had been completed and Liberty served as an inland port with barge connections to the Houston Ship Channel. The population rose steadily from 865 in 1900 to 3,087 in 1940.
During World War II, a camp for German prisoners of war operated at the Liberty fairgrounds. The county fair, first held in 1909, moved to its Wallisville Road grounds in 1930 and with the support of Chambers County became the Trinity Valley Exposition in 1939. Highway 146, which provides a route from East Texas to Baytown and the Texas City-Galveston area, was completed in 1950. In that year a veneer mill, a cannery, a commercial printing plant, and an ice plant contributed to the economy, and a local farmer grew orchids. The population rose to 4,161 in 1950, 5,591 in 1970, and 7,733 in 1990, when the town had 213 businesses. By 2000 there were 8,033 residents and 526 businesses. In the 1960s the Central International Corporation air-milled ingredients for insecticides, and in the 1970s the offices of seventy oil firms were located in the city. The Sam Houston Regional Library and Research Center opened in 1977, and the Geraldine D. Humphreys Cultural Center was open from 1969 to 1984. The nearby home of Governor M. Price Daniel, Sr., built in 1984, is based on the original plans for the Governor's Mansion in Austin.