Texas ( TEK-səss, locally also TEK-siz; Spanish: Texas or Tejas, pronounced [ˈtexas]) is the most populous state in the South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and an international border with the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south and southwest. Texas has a coastline on the Gulf of Mexico to the southeast. Covering 268,596 square miles (695,660 km²), and with some 31 million residents as of 2024, it is the second-largest state by both area and population. Texas is nicknamed the Lone Star State for its former status as an independent republic.

Spain was the first European country to claim and control Texas. Following a short-lived colony controlled by France, Mexico controlled the land until 1836 when Texas won its independence, becoming the Republic of Texas. In 1845, Texas joined the United States of America as the 28th state. The state's annexation set off a chain of events that led to the Mexican–American War in 1846. Following victory by the United States, Texas remained a slave state until the American Civil War, when it declared its secession from the Union in early 1861 before officially joining the Confederate States of America on March 2. After the Civil War and the restoration of its representation in the federal government, Texas entered a long period of economic stagnation.

Historically, five major industries shaped the Texas economy prior to World War II: cattle, bison, cotton, timber, and oil. Before and after the Civil War, the cattle industry—which Texas came to dominate—was a major economic driver and created the traditional image of the Texas cowboy. In the later 19th century, cotton and lumber grew to be major industries as the cattle industry became less lucrative. Ultimately, the discovery of major petroleum deposits (Spindletop in particular) initiated an economic boom that became the driving force behind the economy for much of the 20th century. Texas developed a diversified economy and high tech industry during the mid-20th century. As of 2022, it has the most Fortune 500 company headquarters (53) in the United States. With a growing base of industry, the state leads in many industries, including tourism, agriculture, petrochemicals, energy, computers and electronics, aerospace, and biomedical sciences. Texas has led the U.S. in state export revenue since 2002 and has the second-highest gross state product.

The Dallas–Fort Worth metroplex and Greater Houston areas are the nation's fourth and fifth-most populous urban regions respectively. Its capital city is Austin. Due to its size and geologic features such as the Balcones Fault, Texas contains diverse landscapes common to both the U.S. Southern and the Southwestern regions. Most population centers are in areas of former prairies, grasslands, forests, and the coastline. Traveling from east to west, terrain ranges from coastal swamps and piney woods, to rolling plains and rugged hills, to the desert and mountains of the Big Bend.