The Republic of Texas was an independent nation, bordering the United States and Mexico, that existed from April 21, 1836 to February 19, 1846. The new Republic was formed by the defeat of Mexico in the Texas Revolution and claimed borders that encompassed an area that included all of the present State of Texas, as well as parts of present-day New Mexico, Oklahoma, Kansas, Colorado, and Wyoming.
The northern and western boundaries of the Republic of Texas were very different from present day Texas and included the following areas. From the mouth of the Sabine River north to the 32nd parallel, then due north to the Red River, west to the 100th meridian, north to the Arkansas River and present day Dodge City, Kansas, then west to the headwaters of the Arkansas River near present day Leadville, Colorado and then north to the 42nd parallel, near present day Rawlins, Wyoming. From Silverton, Colorado the western and southern boundary then followed the course of the Rio Grande River.
The Republic of Texas boundaries would thus have included many well known present day areas. Las Cruces, Albuquerque and Taos, New Mexico would be near the boundaries of the west side of the old Republic of Texas. Santa Fe, New Mexico and Alamosa, Colorado would have also been in the Republic of Texas. Rawlings, Wyoming is included as part of the northern border. Kremmling, Vail, and Salida, Colorado would be near the eastern part of the border as would parts of Cañon City and Pueblo, Colorado. Also, La Junta and Lamar, Colorado are found near the boundary line along with the towns of Garden City and Dodge City, Kansas. In addition, there is the “panhandle” strip of Oklahoma that was included in the old Republic of Texas.
How the Republic of Texas Boundaries Were Established
The eastern/northern boundary of Texas was set in 1819 by the Adams-Onís Treaty between the United States and Spain. According to this treaty, the border extended from the mouth of the Sabine River north to the 32nd parallel, then due north to the Red River, west to the 100th meridian, then north to the Arkansas River and present day Dodge City, Kansas, west to the headwaters of the Arkansas River near present day Leadville, Colorado and finally, north to the 42nd parallel near present day Rawlins, Wyoming.
On May 14, 1836, the defeated Mexican President, General Antonio Lopez de Santa Anna, signed the Treaties of Velasco. This treaty established the Republic of Texas as an independent nation and Santa Anna pledged to withdraw his troops south of the Rio Grande River. Setting the Rio Grande river as the southern border would begin the boundary from the Continental Divide West, 10 miles east of present day Silverton, Colorado and follow the course of the river as it flows southward through what is the present day States of New Mexico and Texas and finally out to the Gulf of Mexico. Its total length is approximately 1,896 miles.
The treaty however, was never ratified by the Mexican government and Mexico continued to claim the Nueces River as the boundary. The dispute was not settled until 1848 when the Treaty of Guadalupe Hidalgo was signed by Mexico and the United States. This treaty ended the Mexican War and firmly established the boundary between Mexico and Texas.
The smaller shape of today’s Texas was defined with the Compromise of 1850, in which Texas gave up its claims to vast tracts of western land in exchange for transferring its crushing public debt to the United States. This debt/land exchange resulted in the modern day shape of the State of Texas.