McMillan was named for Texas Ranger Captain Newton D. McMillin in the late 1850s. E.B. House petitioned for a post office to be established here on October 6, 1904, but it opened in Bomar. G.B. Meeks sold his store to local settler Hugh Miller that same year. Only a cemetery remained in 1979 and the community had a population of 15 as of 2000.