n.
State (pop., 2000: 20,851,820), southwestern U.S. Occupying 266,873 sq mi (691,201 sq km), it is the second largest state in both area and population.
Many of Texas's boundaries are formed by water
the course of the Red River on the north makes up two-thirds of the state's boundary with Oklahoma; on the east the state is bordered in part by Arkansas, though the Sabine River forms most of Texas's eastern boundary with Louisiana; the Gulf of Mexico forms the coastal boundary to the southeast; the Rio Grande carves a shallow channel that separates Texas from Mexico on the southwest; the Panhandle section juts northward, forming a counterpart in the western part of Oklahoma; and New Mexico lies to the west. The capital of Texas is Austin . Plains and hills make up the terrain, which ranges from the fertile prairie of the Coastal Plains on the Gulf of Mexico through the central Great Plains grasslands to the arid High Plains of the Panhandle. The forerunners of West Texas Indians inhabited the area as much as 37,000 years ago. Some of the peoples later formed the Caddo confederacy. Indians, including Apache s, were living in the region when the Spanish arrived in 1528. The first settlement was attempted in 1685 by the French, who claimed the region as part of Louisiana. In 1803 the U.S. acquired the French claim in the Louisiana Purchase but relinquished it to Spain by treaty in 1819. It became part of Mexico at Mexican independence in 1821. In 1836 Texans declared independence from Mexico as the Republic of Texas (see Stephen Austin ; Sam Houston ). After a 10-year struggle to remain independent, Texas became the 28th U.S. state in 1845. Its boundary with Mexico was fixed after the Mexican War (1848). In the American Civil War , it seceded from the Union (1861), and it was readmitted in 1870. After the war, railroad building and increased shipping helped expand the economy, and the discovery of oil in 1901 transformed it. While Texas still leads all other states in oil and natural-gas production and in petroleum-refining capacity, its manufacture of electronics, aerospace components, and other high-technology items is increasingly important. It is also the leading cotton, beef-cattle and sheep producer in the U.S.