The United States Census of 1840 was the nation’s sixth decennial enumeration, taken as of June 1, 1840. The official count reported a total population of 17,069,453, an increase of about 32.7 percent over the 1830 census. Of that total, 2,487,355 were recorded as enslaved people, a reminder of the sectional divisions that shaped antebellum American society. The enumeration also placed the national center of population roughly 260 miles west of Washington, D.C., near Weston in what is now West Virginia.

Scope and categories

As with earlier censuses, federal marshals and their assistants visited households and recorded information on preprinted schedules. In 1840 enumerators collected detailed counts by age and sex, recorded the number of "foreigners not naturalized," and tabulated occupational and economic information in broader categories. The 1840 schedules also introduced or emphasized social-health categories that separated counts of people described in contemporary terms as mentally ill or developmentally disabled, and those with sensory impairments; later scholars have used these columns cautiously because classification standards varied by place.

Administration and purpose

The census fulfilled constitutional and statutory roles: apportioning seats in the House of Representatives, guiding the allocation of federal resources, and providing a statistical foundation for state and local planning. Raw counts and aggregated tables were published in official reports that became source material for politicians, economists, and social commentators of the period. Historians today rely on the 1840 returns to study westward migration, urban growth, immigration patterns, labor and manufacturing trends, and the geography of slavery.

Notable results and interpretation

The substantial growth since 1830 reflected sustained high birth rates, immigration, and territorial expansion. The westward shift in the center of population illustrated the continuing movement beyond the original Atlantic seaboard. Because some newer categories were inconsistently reported across states, researchers interpret certain social-health figures with caution; debates about data quality and regional reporting practices are part of the census’s historiography.

Further reading and resources