| | Mountain Brook, AL | Pelham, AL | United States |
| Population | 22,184 | 24,134 | 329,725,481 |
| Female Population | 51.6% | 52.4% | 50.5% |
| Male Population | 48.4% | 47.6% | 49.5% |
| Median Age | 41.9 | 40.6 | 38.4 |
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| Population - 2010 | 20,316 | 21,553 | 309,327,143 |
| Population - 2000 | 20,604 | 14,369 | 285,036,114 |
| Population - 1990 | 19,810 | 9,765 | 251,960,433 |
| Pop. 2000 to Now | -2.8% | 68.6% | 15.6% |
| Pop. 1990 to Now | 1.1% | 148.1% | 30.8% |
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| Population Density | 1,729.8 | 621.7 | 93.4 |
| Land Area | 12.8 | 38.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.5 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Mountain Brook, AL | Pelham, AL | United States |
| Age 0 to 4 | 8.3% | 5.4% | 5.9% |
| Age 5 to 9 | 6.8% | 6.9% | 6.1% |
| Age 10 to 14 | 7.5% | 5.7% | 6.6% |
| Age 15 to 17 | 5.1% | 4.6% | 3.9% |
| Age 18 to 20 | 3.0% | 2.3% | 4.0% |
| Age 21 to 24 | 1.6% | 4.1% | 5.2% |
| Age 25 to 34 | 10.3% | 12.1% | 13.8% |
| Age 35 to 44 | 10.9% | 13.8% | 12.9% |
| Age 45 to 54 | 16.0% | 12.1% | 12.6% |
| Age 55 to 59 | 5.0% | 7.9% | 6.7% |
| Age 60 to 64 | 7.0% | 7.3% | 6.3% |
| Age 65 to 74 | 12.1% | 11.2% | 9.6% |
| Age 75 to 84 | 3.1% | 5.1% | 4.5% |
| Age 85 and over | 3.2% | 1.4% | 1.9% |
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| Race | | | |
| | Mountain Brook, AL | Pelham, AL | United States |
| White | 97.7% | 70.7% | 59.4% |
| Black | 0.4% | 11.1% | 12.2% |
| Asian | 1.0% | 2.6% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.1% | 0.4% |
| Two or More Races | 0.5% | 2.8% | 3.2% |
| Hispanic | 0.2% | 12.5% | 18.4% |
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| Marriage & Family | | | |
| | Mountain Brook, AL | Pelham, AL | United States |
| Married Population | 70.0% | 57.9% | 49.8% |
| Currently Married | 69.9% | 57.7% | 48.0% |
| Married but Separated | 0.1% | 0.2% | 1.8% |
| Single Population | 30.0% | 42.1% | 50.2% |
| Never Married | 21.5% | 23.7% | 33.8% |
| Divorced | 4.5% | 13.6% | 10.8% |
| Widowed | 4.0% | 4.7% | 5.6% |
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| Household Size | 2.65 | 2.60 | 2.60 |
| Households | 8,365 | 9,284 | 124,010,992 |
| Family Households | 6,315 | 6,249 | 80,755,759 |
| Married couple, w/children | 48.8% | 35.2% | 30.5% |
| Married couple, no children | 44.6% | 49.1% | 42.9% |
| Non Family Households | 2,050 | 3,035 | 43,255,233 |
| Single householder, w/children | 3.4% | 10.5% | 15.8% |
| Single householder, no children | 3.2% | 5.2% | 10.8% |