| | St. James, NY | Jericho, NY | United States |
| Population | 13,945 | 14,526 | 329,725,481 |
| Female Population | 51.8% | 52.5% | 50.5% |
| Male Population | 48.2% | 47.5% | 49.5% |
| Median Age | 46.3 | 44.1 | 38.4 |
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| Population - 2010 | 12,774 | 13,011 | 309,327,143 |
| Population - 2000 | 13,268 | 13,045 | 285,036,114 |
| Population - 1990 | 12,703 | 13,141 | 251,960,433 |
| Pop. 2000 to Now | 0.8% | 7.1% | 15.6% |
| Pop. 1990 to Now | 5.3% | 6.4% | 30.8% |
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| Population Density | 3,057.4 | 3,681.2 | 93.4 |
| Land Area | 4.6 | 3.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | St. James, NY | Jericho, NY | United States |
| Age 0 to 4 | 4.4% | 3.9% | 5.9% |
| Age 5 to 9 | 4.1% | 7.6% | 6.1% |
| Age 10 to 14 | 6.8% | 7.9% | 6.6% |
| Age 15 to 17 | 5.1% | 6.0% | 3.9% |
| Age 18 to 20 | 4.8% | 2.6% | 4.0% |
| Age 21 to 24 | 3.8% | 4.2% | 5.2% |
| Age 25 to 34 | 10.7% | 7.6% | 13.8% |
| Age 35 to 44 | 8.7% | 10.9% | 12.9% |
| Age 45 to 54 | 16.1% | 16.2% | 12.6% |
| Age 55 to 59 | 8.5% | 6.9% | 6.7% |
| Age 60 to 64 | 6.6% | 8.6% | 6.3% |
| Age 65 to 74 | 10.3% | 9.9% | 9.6% |
| Age 75 to 84 | 5.3% | 4.3% | 4.5% |
| Age 85 and over | 4.8% | 3.2% | 1.9% |
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| Race | | | |
| | St. James, NY | Jericho, NY | United States |
| White | 86.2% | 51.3% | 59.4% |
| Black | 0.4% | 1.7% | 12.2% |
| Asian | 4.2% | 41.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.6% | 0.4% |
| Two or More Races | 1.2% | 2.5% | 3.2% |
| Hispanic | 7.8% | 3.0% | 18.4% |
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| Marriage & Family | | | |
| | St. James, NY | Jericho, NY | United States |
| Married Population | 54.9% | 65.2% | 49.8% |
| Currently Married | 53.1% | 64.4% | 48.0% |
| Married but Separated | 1.8% | 0.8% | 1.8% |
| Single Population | 45.1% | 34.8% | 50.2% |
| Never Married | 30.0% | 25.5% | 33.8% |
| Divorced | 6.1% | 4.8% | 10.8% |
| Widowed | 9.0% | 4.5% | 5.6% |
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| Household Size | 2.74 | 3.21 | 2.60 |
| Households | 4,927 | 4,480 | 124,010,992 |
| Family Households | 3,520 | 3,744 | 80,755,759 |
| Married couple, w/children | 34.5% | 41.1% | 30.5% |
| Married couple, no children | 46.8% | 48.6% | 42.9% |
| Non Family Households | 1,407 | 736 | 43,255,233 |
| Single householder, w/children | 7.7% | 4.2% | 15.8% |
| Single householder, no children | 10.9% | 6.1% | 10.8% |