Samuel J. P. McDowell, farmer, county leader, and state legislator, was born on July 6, 1824, in Columbia, Tennessee, the son of Irish immigrants. In 1850 he met Sam Houston, then a senator from Texas, in Bolivar, Tennessee. Descriptions of Texas intrigued the young McDowell, and in 1853 he moved to Lockhart in Caldwell County. In 1855 McDowell served with the Callahan Expedition against outlaws and warring American Indians. He traveled back and forth across the Mexican border with Callahan until 1856. From 1856 to 1860 McDowell served as the county clerk for Caldwell County. He married for the first time to Cate L. Shropshire on June 25, 1857, in Lockhart; they had at least one child.
McDowell was elected to the Ninth Texas State Legislature and represented Caldwell, Hays, and Blanco counties until 1862 when he resigned to fight in the Civil War. He was captain of a company of Lockhart volunteers for a time then disbanded the company and went to Camp Terry on the Colorado River south of Austin to join the Seventeenth Regiment of Texas Infantry, part of Walker's Texas Division. McDowell was elected captain of Company K. He fought at Milliken's Bend in Louisiana and was wounded. After the Civil War, McDowell returned to farming and politics in Caldwell County. He was elected again to serve as county clerk from 1873 to 1880. He married for a second time sometime after 1881 to a woman named Rebecca. McDowell was a Presbyterian. When he was almost ninety years old, he was still riding horses and participating in the Caldwell County community. He died in 1920 in Lockhart.