Texas is a state of the United States of America located in the country's Southern and Southwestern regions. With an area of 678,051 km² (261,797 mi²) and a population of 23.5 million in 254 counties, the state is second-largest in both area, behind Alaska, and population, behind California. About half the state's population resides in either the Dallas–Fort Worth or Houston metropolitan areas.
The state's name derives from a word in the Caddoan language of the Hasinai, táyshaʔ, "Friend". Texas declared its independence from Mexico in 1836 and existed as the independent Republic of Texas for nearly a decade. In 1845, it joined the United States as the 28th state.
Texas is internationally known for its energy and aeronautics industries, and for the ship channel at the Port of Houston—the largest in the U.S. in international commerce and the sixth-largest port in the world. The state is home to numerous Fortune 500 companies and has the second-largest economy in the United States. The Texas Medical Center contains the world's largest concentration of research and healthcare institutions.