| | St. James, MO | Kansas City, MO | United States |
| Population | 3,970 | 502,597 | 329,725,481 |
| Female Population | 51.5% | 51.5% | 50.5% |
| Male Population | 48.5% | 48.5% | 49.5% |
| Median Age | 30.3 | 35.4 | 38.4 |
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| Population - 2010 | 4,215 | 460,690 | 309,327,143 |
| Population - 2000 | 3,704 | 441,545 | 285,036,114 |
| Population - 1990 | 3,256 | 435,146 | 251,960,433 |
| Pop. 2000 to Now | 8.2% | 12.6% | 15.6% |
| Pop. 1990 to Now | 23.0% | 14.3% | 30.8% |
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| Population Density | 928.7 | 1,596.1 | 93.4 |
| Land Area | 4.3 | 314.9 | 3,531,905.4 |
| Water Area | 0.0 | 4.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | St. James, MO | Kansas City, MO | United States |
| Age 0 to 4 | 11.0% | 6.4% | 5.9% |
| Age 5 to 9 | 7.9% | 6.5% | 6.1% |
| Age 10 to 14 | 11.1% | 6.4% | 6.6% |
| Age 15 to 17 | 4.6% | 3.6% | 3.9% |
| Age 18 to 20 | 1.5% | 3.4% | 4.0% |
| Age 21 to 24 | 5.6% | 5.5% | 5.2% |
| Age 25 to 34 | 16.4% | 17.7% | 13.8% |
| Age 35 to 44 | 7.5% | 13.3% | 12.9% |
| Age 45 to 54 | 8.6% | 11.7% | 12.6% |
| Age 55 to 59 | 8.4% | 6.2% | 6.7% |
| Age 60 to 64 | 4.1% | 6.0% | 6.3% |
| Age 65 to 74 | 5.5% | 8.3% | 9.6% |
| Age 75 to 84 | 4.8% | 3.4% | 4.5% |
| Age 85 and over | 3.1% | 1.7% | 1.9% |
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| Race | | | |
| | St. James, MO | Kansas City, MO | United States |
| White | 90.0% | 55.5% | 59.4% |
| Black | 0.7% | 26.3% | 12.2% |
| Asian | 0.6% | 2.6% | 5.6% |
| Native American | 0.7% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.0% | 0.4% | 0.4% |
| Two or More Races | 2.3% | 4.0% | 3.2% |
| Hispanic | 5.7% | 10.7% | 18.4% |
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| Marriage & Family | | | |
| | St. James, MO | Kansas City, MO | United States |
| Married Population | 50.2% | 42.6% | 49.8% |
| Currently Married | 47.3% | 40.6% | 48.0% |
| Married but Separated | 2.9% | 2.0% | 1.8% |
| Single Population | 49.8% | 57.4% | 50.2% |
| Never Married | 27.7% | 39.3% | 33.8% |
| Divorced | 15.1% | 13.3% | 10.8% |
| Widowed | 7.0% | 4.8% | 5.6% |
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| Household Size | 2.54 | 2.31 | 2.60 |
| Households | 1,464 | 213,560 | 124,010,992 |
| Family Households | 1,033 | 114,540 | 80,755,759 |
| Married couple, w/children | 33.8% | 29.0% | 30.5% |
| Married couple, no children | 25.8% | 38.1% | 42.9% |
| Non Family Households | 431 | 99,020 | 43,255,233 |
| Single householder, w/children | 36.0% | 20.2% | 15.8% |
| Single householder, no children | 4.4% | 12.7% | 10.8% |