Greer County, created by the Texas legislature on February 8, 1860, and named for John Alexander Greer, a Texas lieutenant governor, was land claimed by both Texas and the United States. The dispute arose from a map submitted with the Adams-Onís Treaty of 1819. The treaty stated that the boundary between the French claims on the north and the Spanish claims on the south of the United States was the Rio Roxo de Natchitoches (Red River) until it reached the 100th meridian west, as noted on John Melish's map published in 1818. However, the upper reaches of the Red River were not surveyed, as required by the fourth article of the treaty, until 1852. The problem was that the 100th meridian on the Melish map was approximately east of the true 100th meridian and the Red River forked about east of the 100th meridian. Another survey team discovered the mapping error in 1857 and showed that the southern fork was the Red River should be the correct boundary described by the Adams–Onís Treaty. Texas rejected that assertion and claimed the land south of the North Fork. The United States claimed the land north of the South Fork (previously named the Prairie Dog Town River).