| | Smithville, MO | Leavenworth, KS | United States |
| Population | 10,211 | 37,216 | 329,725,481 |
| Female Population | 52.6% | 45.5% | 50.5% |
| Male Population | 47.4% | 54.5% | 49.5% |
| Median Age | 36.4 | 36.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,423 | 35,380 | 309,327,143 |
| Population - 2000 | 5,514 | 35,420 | 285,036,114 |
| Population - 1990 | 2,525 | 38,495 | 251,960,433 |
| Pop. 2000 to Now | 99.7% | 1.5% | 15.6% |
| Pop. 1990 to Now | 336.1% | -6.7% | 30.8% |
| space4 | | | |
| Population Density | 653.4 | 1,518.9 | 93.4 |
| Land Area | 15.6 | 24.5 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Smithville, MO | Leavenworth, KS | United States |
| Age 0 to 4 | 9.3% | 7.5% | 5.9% |
| Age 5 to 9 | 8.0% | 7.3% | 6.1% |
| Age 10 to 14 | 5.2% | 5.8% | 6.6% |
| Age 15 to 17 | 7.2% | 2.7% | 3.9% |
| Age 18 to 20 | 3.8% | 3.3% | 4.0% |
| Age 21 to 24 | 3.7% | 6.3% | 5.2% |
| Age 25 to 34 | 10.7% | 13.5% | 13.8% |
| Age 35 to 44 | 14.5% | 15.9% | 12.9% |
| Age 45 to 54 | 12.1% | 11.3% | 12.6% |
| Age 55 to 59 | 7.6% | 7.0% | 6.7% |
| Age 60 to 64 | 4.1% | 5.9% | 6.3% |
| Age 65 to 74 | 8.8% | 8.3% | 9.6% |
| Age 75 to 84 | 3.9% | 4.2% | 4.5% |
| Age 85 and over | 1.1% | 1.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Smithville, MO | Leavenworth, KS | United States |
| White | 91.5% | 70.6% | 59.4% |
| Black | 0.6% | 11.1% | 12.2% |
| Asian | 1.0% | 1.7% | 5.6% |
| Native American | 0.3% | 0.6% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 5.5% | 7.0% | 3.2% |
| Hispanic | 1.1% | 8.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Smithville, MO | Leavenworth, KS | United States |
| Married Population | 57.5% | 52.2% | 49.8% |
| Currently Married | 56.8% | 49.4% | 48.0% |
| Married but Separated | 0.6% | 2.7% | 1.8% |
| Single Population | 42.5% | 47.8% | 50.2% |
| Never Married | 26.8% | 28.5% | 33.8% |
| Divorced | 11.5% | 13.9% | 10.8% |
| Widowed | 4.2% | 5.3% | 5.6% |
| space5 | | | |
| Household Size | 2.74 | 2.49 | 2.60 |
| Households | 3,694 | 13,554 | 124,010,992 |
| Family Households | 2,861 | 8,504 | 80,755,759 |
| Married couple, w/children | 42.6% | 34.2% | 30.5% |
| Married couple, no children | 32.7% | 44.1% | 42.9% |
| Non Family Households | 833 | 5,050 | 43,255,233 |
| Single householder, w/children | 14.2% | 16.0% | 15.8% |
| Single householder, no children | 10.5% | 5.8% | 10.8% |