Houston is the largest city in the state of Texas, and the fourth-largest city in the United States. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of 579 square miles (1,500 km2). Houston is the seat of Harris County and the economic center of Houston–Sugar Land–Baytown, which is the sixth-largest metropolitan area in the U.S. of nearly 6 million people.
Houston was founded in 1836 on land near the banks of Buffalo Bayou. It was incorporated as a city on June 5, 1837, and named after then-President of the Republic of Texas—former General Sam Houston—who had commanded at the Battle of San Jacinto, which took place 25 miles (40 km) east of where the city was established. The burgeoning port and railroad industry, combined with oil discovery in 1901, has induced continual surges in the city's population. In the mid-twentieth century, Houston became the home of the Texas Medical Center—the world's largest concentration of healthcare and research institutions—and NASA's Johnson Space Center, where the Mission Control Center is located.
Rated as a global city, Houston's economy has a broad industrial base in energy, manufacturing, aeronautics, and transportation. It is also leading in health care sectors and building oilfield equipment; only New York City is home to more Fortune 500 headquarters. The Port of Houston ranks first in the United States in international waterborne tonnage handled and second in total cargo tonnage handled. The city has a population from various ethnic and religious backgrounds and a large and growing international community. It is home to many cultural institutions and exhibits, which attract more than 7 million visitors a year to the Museum District. Houston has an active visual and performing arts scene in the Theater District and offers year-round resident companies in all major performing arts.According to the United States Census Bureau, the city has a total area of 601.7 square miles (1,558 km2); this comprises 579.4 square miles (1,501 km2) of land and 22.3 square miles (58 km2) of water. Most of Houston is located on the gulf coastal plain, and its vegetation is classified as temperate grassland and forest. Much of the city was built on forested land, marshes, swamp, or prairie, which are all still visible in surrounding areas. Flatness of the local terrain, when combined with urban sprawl, has made flooding a recurring problem for the city. Downtown stands about 50 feet (15 m) above sea level, and the highest point in far northwest Houston is about 125 feet (38 m) in elevation. The city once relied on groundwater for its needs, but land subsidence forced the city to turn to ground-level water sources such as Lake Houston, Lake Conroe and Lake Livingston.
The city owns surface water rights for 1.2 billion gallons of water a day in addition to 150 million gallons a day worth of groundwater.
Houston has four major bayous passing through the city. Buffalo Bayou runs through downtown and the Houston Ship Channel, and has three tributaries: White Oak Bayou, which runs through the Houston Heights community northwest of Downtown and then towards Downtown; Braes Bayou, which runs along the Texas Medical Center; and Sims Bayou, which runs through the south of Houston and downtown Houston. The ship channel continues past Galveston and then into the Gulf of Mexico.