The United States Census of 1840 was the sixth census of the United States. It was completed on June 1, 1840. It found the population of the United States to be 17,069,453. This was an increase of 32.7 percent from the 1830 Census. The total population included 2,487,355 slaves. In 1840, the center of population was about 260 miles (418 km) west of Washington, D.C., near Weston, West Virginia.