1840
Source data for population is available from the Census Bureau.
| Rank | City | State | Population | Notes |
| 1 | New York | New York | 312,710 | |
| 2 | Baltimore | Maryland | 102,313 | Baltimore is likely the second city to surpass the 100,000 population mark. |
| 3 | New Orleans | Louisiana | 102,193 | New Orleans' rapid growth shows the increasing importance of Mississippi River trade. |
| 4 | Philadelphia | Pennsylvania | 93,665 | |
| 5 | Boston | Massachusetts | 93,383 | |
| 6 | Cincinnati | Ohio | 46,338 | Listed as a town. |
| 7 | Brooklyn | New York | 36,233 | At this time, Brooklyn was a city. |
| 8 | Northern Liberties | Pennsylvania | 34,474 | Now a neighborhood in Philadelphia. |
| 9 | Albany | New York | 33,721 | |
| 10 | Charleston | South Carolina | 29,261 | Charleston lost population between the 1830 and 1840 censuses. Last appearance in the top 10. |
Read more about this topic: Largest Cities In The United States By Population By Decade