Houston is the most populous city in Texas and the fourth most populous city in the United States. According to the 2012 U.S. Census estimates, the city had a population of 2.16 million people within a land area of 599.6 square miles (1,553 km2). Houston is the seat of Harris County, and its metropolitan area is the fifth-most populated in the U.S., with over 6 million people. Houston was founded in 1836 on land near the banks of Buffalo Bayou (now known as Allen's Landing) and incorporated as a city on June 5, 1837. The city was named after former General Sam Houston, who was president of the Republic of Texas and had commanded and won at the Battle of San Jacinto 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. 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.