Alexander, at the junction of State Highway 6 and Farm Road 914 in southern Erath County, was named Harper's Mill when a post office was established there in 1876. John D. St. Clair was the first postmaster and was still serving in 1881, when the name was changed to Alexander, possibly after an official of the Texas Central Railroad Company. The railroad laid out the townsite after buying land from W. C. Keith in 1880. Alexander expanded after the railroad came in 1881, but growth was checked after the railroad reached Stephenville in 1889. Alexander had a population of 381 and twenty-one businesses in 1890. In 1900 the population was the same, but the number of businesses had declined. By 1940 the town had 200 people, a post office, and five businesses. The post office closed before 1970, when the population was forty. In 2000 the population was still reported as forty.