Old Union is located on U.S. 67 about nine miles southwest of New Boston and twenty-five miles southwest of Texarkana in southern Bowie County. Settlement may have begun as early as 1830, when school was conducted out of a log-hewn house in the area. The schoolhouse also held church services for various denominations, and the name Union was derived from the Union Church. Martin A. Poer was the original grantee of the land where Old Union was established, and he received his patent on May 15, 1848. Social activities in the farming settlement probably centered on school and church functions. Old Union Cemetery was established by the 1860s, and the earliest marked graves date to the mid-1860s. In the early part of the twentieth century through the 1930s Old Union had a school, two Baptist churches, several businesses, and many farms and homes. The cemetery was still in use in the latter 1900s, and in 1990 the town had a population of 238. That figure remained constant through 2000.