| | Washington Grove, MD | Summit, NJ | United States |
| Population | 700 | 22,598 | 329,725,481 |
| Female Population | 45.6% | 51.9% | 50.5% |
| Male Population | 54.4% | 48.1% | 49.5% |
| Median Age | 55.5 | 39.7 | 38.4 |
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| Population - 2010 | 523 | 21,493 | 309,327,143 |
| Population - 2000 | 515 | 21,131 | 285,036,114 |
| Population - 1990 | 434 | 19,757 | 251,960,433 |
| Pop. 2000 to Now | 7.0% | 3.2% | 15.6% |
| Pop. 1990 to Now | 27.0% | 10.4% | 30.8% |
| space4 | | | |
| Population Density | 2,058.8 | 3,770.1 | 93.4 |
| Land Area | 0.3 | 6.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Washington Grove, MD | Summit, NJ | United States |
| Age 0 to 4 | 3.7% | 7.4% | 5.9% |
| Age 5 to 9 | 6.3% | 6.2% | 6.1% |
| Age 10 to 14 | 0.1% | 8.6% | 6.6% |
| Age 15 to 17 | 3.7% | 5.5% | 3.9% |
| Age 18 to 20 | 2.0% | 3.3% | 4.0% |
| Age 21 to 24 | 5.7% | 3.6% | 5.2% |
| Age 25 to 34 | 6.9% | 7.7% | 13.8% |
| Age 35 to 44 | 7.6% | 15.5% | 12.9% |
| Age 45 to 54 | 12.1% | 16.4% | 12.6% |
| Age 55 to 59 | 12.7% | 7.5% | 6.7% |
| Age 60 to 64 | 14.1% | 5.8% | 6.3% |
| Age 65 to 74 | 18.9% | 6.2% | 9.6% |
| Age 75 to 84 | 4.1% | 4.1% | 4.5% |
| Age 85 and over | 2.0% | 2.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Washington Grove, MD | Summit, NJ | United States |
| White | 78.1% | 66.7% | 59.4% |
| Black | 10.7% | 7.0% | 12.2% |
| Asian | 2.3% | 9.1% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 1.5% | 0.4% |
| Two or More Races | 3.1% | 4.0% | 3.2% |
| Hispanic | 5.7% | 11.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Washington Grove, MD | Summit, NJ | United States |
| Married Population | 46.9% | 55.8% | 49.8% |
| Currently Married | 46.9% | 55.1% | 48.0% |
| Married but Separated | 0.0% | 0.6% | 1.8% |
| Single Population | 53.1% | 44.2% | 50.2% |
| Never Married | 27.8% | 32.8% | 33.8% |
| Divorced | 18.0% | 6.7% | 10.8% |
| Widowed | 7.3% | 4.7% | 5.6% |
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| Household Size | 2.19 | 2.85 | 2.60 |
| Households | 319 | 7,853 | 124,010,992 |
| Family Households | 170 | 5,687 | 80,755,759 |
| Married couple, w/children | 25.9% | 49.9% | 30.5% |
| Married couple, no children | 58.2% | 31.4% | 42.9% |
| Non Family Households | 149 | 2,166 | 43,255,233 |
| Single householder, w/children | 10.0% | 8.7% | 15.8% |
| Single householder, no children | 5.9% | 10.0% | 10.8% |