| | Brunswick, MD | Gaithersburg, MD | United States |
| Population | 7,578 | 68,827 | 329,725,481 |
| Female Population | 48.2% | 51.4% | 50.5% |
| Male Population | 51.8% | 48.6% | 49.5% |
| Median Age | 37 | 37.6 | 38.4 |
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| Population - 2010 | 5,890 | 60,178 | 309,327,143 |
| Population - 2000 | 4,894 | 52,613 | 285,036,114 |
| Population - 1990 | 5,117 | 39,542 | 251,960,433 |
| Pop. 2000 to Now | 35.9% | 28.8% | 15.6% |
| Pop. 1990 to Now | 30.0% | 71.3% | 30.8% |
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| Population Density | 2,321.0 | 6,670.6 | 93.4 |
| Land Area | 3.3 | 10.3 | 3,531,905.4 |
| Water Area | 0.4 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Brunswick, MD | Gaithersburg, MD | United States |
| Age 0 to 4 | 5.7% | 7.0% | 5.9% |
| Age 5 to 9 | 6.0% | 6.1% | 6.1% |
| Age 10 to 14 | 6.8% | 6.2% | 6.6% |
| Age 15 to 17 | 5.8% | 3.5% | 3.9% |
| Age 18 to 20 | 3.6% | 3.4% | 4.0% |
| Age 21 to 24 | 3.3% | 4.7% | 5.2% |
| Age 25 to 34 | 13.7% | 13.9% | 13.8% |
| Age 35 to 44 | 15.1% | 16.9% | 12.9% |
| Age 45 to 54 | 16.7% | 13.7% | 12.6% |
| Age 55 to 59 | 6.2% | 6.4% | 6.7% |
| Age 60 to 64 | 6.6% | 5.7% | 6.3% |
| Age 65 to 74 | 7.3% | 7.3% | 9.6% |
| Age 75 to 84 | 2.4% | 3.3% | 4.5% |
| Age 85 and over | 0.6% | 2.0% | 1.9% |
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| Race | | | |
| | Brunswick, MD | Gaithersburg, MD | United States |
| White | 73.4% | 33.7% | 59.4% |
| Black | 9.5% | 16.4% | 12.2% |
| Asian | 1.5% | 20.4% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.4% | 0.4% |
| Two or More Races | 9.3% | 4.2% | 3.2% |
| Hispanic | 6.2% | 24.5% | 18.4% |
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| Marriage & Family | | | |
| | Brunswick, MD | Gaithersburg, MD | United States |
| Married Population | 53.8% | 53.4% | 49.8% |
| Currently Married | 52.6% | 51.9% | 48.0% |
| Married but Separated | 1.1% | 1.5% | 1.8% |
| Single Population | 46.2% | 46.6% | 50.2% |
| Never Married | 32.8% | 32.6% | 33.8% |
| Divorced | 10.6% | 9.8% | 10.8% |
| Widowed | 2.8% | 4.2% | 5.6% |
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| Household Size | 2.66 | 2.64 | 2.60 |
| Households | 2,851 | 25,945 | 124,010,992 |
| Family Households | 1,901 | 17,217 | 80,755,759 |
| Married couple, w/children | 40.9% | 38.0% | 30.5% |
| Married couple, no children | 41.0% | 36.9% | 42.9% |
| Non Family Households | 950 | 8,728 | 43,255,233 |
| Single householder, w/children | 10.9% | 12.7% | 15.8% |
| Single householder, no children | 7.2% | 12.4% | 10.8% |