Mount Pleasant is the county seat of and largest city in Titus County, in the U.S. state of Texas. As of the 2020 census, Mount Pleasant's popula…Mount Pleasant is the county seat of and largest city in Titus County, in the U.S. state of Texas. As of the 2020 census, Mount Pleasant's population was 16,047; it is situated in Northeast Texas. Mount Pleasant was founded May 11, 1848, to serve as county seat for Titus County, which was created by a legislative act on May 11, 1846. Until after the Civil War, Titus County also included the territory of present-day Franklin and Morris Counties. High waters along the creeks and the Sulphur River often halted travel in the early years.