By 1848 the United States government established a post office, and in 1849 a formal town site was laid out on land donated by Stephen and Rebecca Keith for the town of Mount Vernon. Since there were two other Mount Vernons in Texas, the post office was called "Keith" and then "Lone Star" before the name "Mount Vernon" became available in 1875. Franklin County was carved out of Titus County in 1875, and Mount Vernon was elected county seat in competition with other communities.