Kansas City is the largest city in Missouri and the sixth largest city in the Midwest. According to the U.S. Census Bureau, the city had an estimated population of 475,378 in 2015, making it the 36th largest city by population in the United States. It is the anchor city of the Kansas City metropolitan area, which straddles the Kansas–Missouri border. Kansas City was founded in the 1830s as a Missouri River port at its confluence with the Kansas River coming in from the west. On June 1, 1850 the town of Kansas was incorporated; shortly after came the establishment of the Kansas Territory. Confusion between the two ensued and the name Kansas City was assigned to distinguish them soon thereafter. Sitting on Missouri's western border, with Downtown near the confluence of the Kansas and Missouri rivers, the modern city encompasses some 319.03 square miles (826.3 km2), making it the 23rd largest city by total area in the United States. Most of the city lies within Jackson County, but portions spill into Clay, Cass, and Platte counties. Along with Independence, it serves as one of the two county seats for Jackson County. Major suburbs include the Missouri cities of Independence and Lee's Summit and the Kansas cities of Overland Park, Olathe, and Kansas City.