Founded in 1836 by brothers Augustus Chapman Allen and John Kirby Allen, Houston houses around 2.3 million people on its approximate 600 square miles of land. It was incorporated the following year and given its name after its president at the time, former General Sam Houston. One reason the population keeps increasing is due to the expanding railroad and port industry as well as oil discovery in 1901. Later on it became home to Texas Medical Center (a worldwide leader in healthcare and research) and NASA Johnson Space Center.