Spanish Cession - Later Developments

Later Developments

The treaty was ratified by Spain in 1820, and by the United States in 1821 (during the time that Spain and Mexico were engaged in the prolonged Mexican War of Independence). Spain finally recognized the independence of Mexico with the Treaty of Córdoba signed on August 24, 1821. While Mexico was not initially a party to the treaty, in 1831 Mexico ratified the treaty.

By the mid-1830s, a controversy developed regarding the border with Texas, during which the United States demonstrated that the Sabine and Neches rivers had been switched on maps, moving the frontier in favor of Mexico. As a consequence, the eastern boundary of Texas was not firmly established until the independence of the Republic of Texas in 1836. It was not agreed upon by the United States and Mexico until the Treaty of Guadalupe Hidalgo in 1848, which concluded the Mexican-American War. The Treaty of Guadalupe Hidalgo formalized the cession by Mexico of Alta California and today's American Southwest, except for the territory of the later Gadsden Purchase of 1854.

Another dispute occurred after Texas joined the Union. The treaty stated that the boundary between the French claims on the north and the Spanish claims on the south was Rio Roxo de Natchitoches (Red River) until it reached the 100th meridian, as noted on the John Melish map of 1818. But, the 100th meridian on the Melish map was marked some 90 miles east of the true 100th meridian, and the Red River forked about 50 miles east of the 100th meridian. Texas claimed the land south of the North Fork, and the United States claimed the land north of the South Fork (later called the Prairie Dog Town Fork Red River). In 1860 Texas organized the area as Greer County. The matter was not settled until a United States Supreme Court ruling in 1896 upheld federal claims to the territory, after which it was added to the Oklahoma Territory.