Mt. Vernon was established in 1849 on land donated by Stephen and Rebecca Keith, and a public square was surveyed in the 24-acre plat. When Franklin County was created in 1875, Mt. Vernon was voted county seat, and a wooden building northeast of the square served as the first courthouse. Lots on the block north of the square were soon purchased for $150 for a 2-story wooden jail costing $1,600. In 1878 a brick courthouse was built on the square at a cost of $5,500. In 1910 county commissioners ordered an election to decide the building of a new courthouse and jail, then rescinded that order, called for construction warrants to be issued without an election, and levied a property tax to pay for the new buildings. Citizens sued the county, and in January 1911 the district court prevented construction from proceeding, but an appellate court overturned the decision and by December 1911 the Texas Supreme Court had affirmed this method of financing county buildings. Within days of that decision, Franklin County commissioners awarded a contract to L. R. Wright & Co. to construct the courthouse and adjacent jail, and the buildings were completed in 1912 at a cost of $55,000.