The geographical borders of Texas are complicated due to its unusual shape, and they do not follow typical east/west or north/south divisions. A historical land deal transferred Texan debt to the United States government in exchange for large chunks of western land in the Compromise of 1850. Texas now borders on four other states as well as the Gulf of Mexico and the country of Mexico. At 268,601 square miles, Texas is the second largest state; only Alaska is bigger. Almost 262,000 square miles are land masses, but the remaining, 6,700 square miles of water area make it the ninth wettest state.
New Mexico: Changing Borders
Beginning from the Texas/New Mexico/Mexico junction near El Paso, the border is a winding state line that roughly follows the Rio Grande River northward. When it reaches the 32nd parallel, the state border hangs a sharp right along the route once considered as the southern route of the Texas Western Railroad Company. The border between the two states hasn't always been so clear-cut. Both states agreed that the border was the middle of the Rio Grande as it was located in 1850, but the two states had different ideas of where the Rio Grande had really been located that year. The case was taken to the U.S. Supreme Court in 1927.
Oklahoma: Where the Panhandles Meet
Parallel 36°30′ north was historically the dividing line for slave-owning states and free states. Following the Missouri Compromise in 1820, only states south of this line allowed people to own slaves. The line now forms part of the border between the Texas and Oklahoma Panhandles. The Panhandle of Texas is a rectangular land mass of 26 counties and 25,610 square miles, with the boundaries of the 100th meridian in the east, parallel 36°30' in the north, 103rd meridian in the west and the southern boundary of Swisher County to the south. East of the Panhandle, the boundary between Texas and Oklahoma roughly follows the Red River.
Louisiana: The Sabine River
The long eastern border between Louisiana and Texas is marked primarily by the Sabine River. This dates back to the Adams-Onís Treaty of 1819, when the eastern boundary of Texas was established as starting at the Gulf of Mexico and following the Sabine River to the 32nd parallel. A longtime dispute has led to numerous court battles between Texas and Louisiana over which bank of the river belongs to each state. The Texas state line extends slightly past the Louisiana northern border to intersect with the state of Arkansas.
Arkansas-Texas: Home of a Unique Post Office
The only post office in the United States to straddle two different states is found in the city of Texarkana on the Texas-Arkansas border. The current border of the two states begins at Louisiana's northwest border. It then runs north to the Red River's south bank and west to Oklahoma. Significant controversy has plagued this boundary line for many years, with Spain and President Jefferson nearly ending up in a war because of a boundary dispute. It was resolved through an 1838 treaty between Mexico, Spain and the Republic of Texas.
Gulf of Mexico: Beaches From Border to Border
The southeast border of Texas curves 367 miles along the Gulf of Mexico, stretching from South Padre Island all the way to the Louisiana border. This is a highly populated area of the state. It is however, at risk of hurricanes making landfall after they form in or travel through the Gulf.
Mexico: Our Southern Neighbor
The southwest side of the state forms part of the country's second longest international border with its Mexican neighbor. At 1,241 miles in length, the Texas-Mexico border makes up the largest percentage of the country's 1,933 mile border with Mexico. There are 26 international border crossings along this stretch, mostly bridges.
The boundaries of the Republic of Texas were much larger than the present-day state. Formed after Mexico's defeat in the Texas Revolution, the Republic existed as an independent body from April 21, 1836, to February 19, 1846. Its boundaries included the current land mass of the State of Texas, the bordering states of New Mexico and Oklahoma, and sections of land that now belong to Wyoming, Kansas and Colorado.