Joshua Foster Johnson came to Texas from Tennessee in 1845, settling in 1846 near the site of Mount Vernon, which he helped found as the town of Keith in 1848. He served in the 3rd Texas Legislature in 1849-50 and sponsored the bill for the Mount Vernon Male and Female Academies, leading to the public school system. He was a member of the Secession Convention in 1861 and the Constitutional Convention in 1875. As a pastor, he helped organize Mount Vernon Baptist Church. He married Amanda C. Wright, and they had seven sons and three daughters.