Belle Plain, six miles southeast of Baird in Callahan County, was established in 1876. Nelson M. Smith purchased state school land for the site in 1875 and laid out a town with wide streets and a designated business district. The site was intended to become a commercial center for the county. Some attribute the name of the community to some bell-shaped contour in the surrounding country, but more likely it was the name of the first child born at the townsite, Katie Belle Magee. By the summer of 1876, the town had three businesses, including a saloon operated by J. W. Cheatham. After Callahan County was formally organized in 1877, voters selected Belle Plain over nearby Callahan City as the first county seat. The new county seat prospered, drawing citizens from Callahan City and other smaller towns as well as new settlers. It eventually had several stores and saloons, a stone jail, two fraternal lodges, eleven lawyers, and four physicians. A newspaper, the Callahan County Clarendon, was begun in 1879. The population was never large (about 400 in 1884), but the town served as a regional supply center and exporter of wool, hides, and cotton.
The pride of Belle Plain was Belle Plain College, and both college and community declined simultaneously. When the railroad was built through Baird, some citizens moved there. In 1883 Baird became the county seat, and the population of Belle Plain diminished further. The town's newspaper moved to Baird that year, and the stone jail was eventually disassembled and rebuilt in the new county seat. The region was also damaged by the hard winter of 1884–85 and the drought of 1886–87. After a financial struggle, the college closed in 1892. With the college gone, the county government lost, and most of the population moved away, Belle Plain was doomed. In 1897 only four families and one small store remained in the area. The post office was belatedly discontinued in October 1909.