| | Bryn Mawr, PA | Mountain Brook, AL | United States |
| Population | 5,573 | 22,184 | 329,725,481 |
| Female Population | 59.2% | 51.6% | 50.5% |
| Male Population | 40.8% | 48.4% | 49.5% |
| Median Age | 29.5 | 41.9 | 38.4 |
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| Population - 2010 | 3,510 | 20,316 | 309,327,143 |
| Population - 2000 | 4,382 | 20,604 | 285,036,114 |
| Population - 1990 | 3,271 | 19,810 | 251,960,433 |
| Pop. 2000 to Now | -17.6% | -2.8% | 15.6% |
| Pop. 1990 to Now | 10.4% | 1.1% | 30.8% |
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| Population Density | 8,790.2 | 1,729.8 | 93.4 |
| Land Area | 0.6 | 12.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Bryn Mawr, PA | Mountain Brook, AL | United States |
| Age 0 to 4 | 1.6% | 8.3% | 5.9% |
| Age 5 to 9 | 2.7% | 6.8% | 6.1% |
| Age 10 to 14 | 3.5% | 7.5% | 6.6% |
| Age 15 to 17 | 3.1% | 5.1% | 3.9% |
| Age 18 to 20 | 18.6% | 3.0% | 4.0% |
| Age 21 to 24 | 14.1% | 1.6% | 5.2% |
| Age 25 to 34 | 13.5% | 10.3% | 13.8% |
| Age 35 to 44 | 9.0% | 10.9% | 12.9% |
| Age 45 to 54 | 8.6% | 16.0% | 12.6% |
| Age 55 to 59 | 5.3% | 5.0% | 6.7% |
| Age 60 to 64 | 5.2% | 7.0% | 6.3% |
| Age 65 to 74 | 7.1% | 12.1% | 9.6% |
| Age 75 to 84 | 5.5% | 3.1% | 4.5% |
| Age 85 and over | 2.3% | 3.2% | 1.9% |
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| Race | | | |
| | Bryn Mawr, PA | Mountain Brook, AL | United States |
| White | 66.6% | 97.7% | 59.4% |
| Black | 9.0% | 0.4% | 12.2% |
| Asian | 8.1% | 1.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.3% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 5.7% | 0.5% | 3.2% |
| Hispanic | 10.3% | 0.2% | 18.4% |
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| Marriage & Family | | | |
| | Bryn Mawr, PA | Mountain Brook, AL | United States |
| Married Population | 32.5% | 70.0% | 49.8% |
| Currently Married | 30.8% | 69.9% | 48.0% |
| Married but Separated | 1.6% | 0.1% | 1.8% |
| Single Population | 67.5% | 30.0% | 50.2% |
| Never Married | 56.1% | 21.5% | 33.8% |
| Divorced | 7.4% | 4.5% | 10.8% |
| Widowed | 4.1% | 4.0% | 5.6% |
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| Household Size | 2.13 | 2.65 | 2.60 |
| Households | 1,885 | 8,365 | 124,010,992 |
| Family Households | 931 | 6,315 | 80,755,759 |
| Married couple, w/children | 28.2% | 48.8% | 30.5% |
| Married couple, no children | 49.4% | 44.6% | 42.9% |
| Non Family Households | 954 | 2,050 | 43,255,233 |
| Single householder, w/children | 7.8% | 3.4% | 15.8% |
| Single householder, no children | 14.5% | 3.2% | 10.8% |