The lands in what are now Lavaca County were in the grants of both Stephen F. Austin and Green C. DeWitt. In 1831, DeWitt allocated land grants to twenty-one and Austin to twelve families who came to establish homes.
In 1833, John Hallet located on a league of land on the east bank of the Lavaca River. Here he built a small log cabin, but made no effort to put in a crop, and returned to his former home in Goliad where he died in 1836.
Following the death of her husband, Margaret Hallet moved from Goliad to the cabin on the Lavaca. She stocked it with a small supply of merchandise and within a short time other pioneers settled nearby on both sides of the river. These formed the nucleus for the Hallet settlement.
In 1842, the Texas Congress created a "Judicial" county from the fragments of Fayette, Colorado, Jackson, Victoria and Gonzales counties, naming it LaBaca. In 1846, Lavaca became a regularly constituted county. Petersburg and Hallettsville both wanted the county seat, but after two elections and a violent contest, Hallettsville was declared the seat of the government in 1852 and Petersburg went into decline.
Following the Civil War, Czechs and Germans began settling around Hallettsville, changing it from a simple trading post to the agricultural center of the county. While forging ahead, the community has not forgotten its past. There are a number of state historical markers in the town and Hallettsville has memorialized many of its pioneer settlers in a memorial park