| | Lake Mathews, CA | Martinsville, VA | United States |
| Population | 7,455 | 13,476 | 329,725,481 |
| Female Population | 47.3% | 53.7% | 50.5% |
| Male Population | 52.7% | 46.4% | 49.5% |
| Median Age | 40.6 | 40.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 6,002 | 13,786 | 309,327,143 |
| Population - 2000 | 3,555 | 15,416 | 285,036,114 |
| Population - 1990 | 3,151 | 16,162 | 251,960,433 |
| Pop. 2000 to Now | 91.2% | -19.9% | 15.6% |
| Pop. 1990 to Now | 115.7% | -23.6% | 30.8% |
| space4 | | | |
| Population Density | 468.1 | 1,230.0 | 93.4 |
| Land Area | 15.9 | 11.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Lake Mathews, CA | Martinsville, VA | United States |
| Age 0 to 4 | 5.3% | 7.3% | 5.9% |
| Age 5 to 9 | 6.0% | 7.1% | 6.1% |
| Age 10 to 14 | 9.2% | 6.9% | 6.6% |
| Age 15 to 17 | 7.7% | 4.0% | 3.9% |
| Age 18 to 20 | 4.0% | 4.3% | 4.0% |
| Age 21 to 24 | 3.5% | 4.3% | 5.2% |
| Age 25 to 34 | 8.9% | 10.3% | 13.8% |
| Age 35 to 44 | 11.7% | 11.3% | 12.9% |
| Age 45 to 54 | 14.3% | 13.0% | 12.6% |
| Age 55 to 59 | 7.7% | 7.1% | 6.7% |
| Age 60 to 64 | 6.7% | 7.0% | 6.3% |
| Age 65 to 74 | 9.0% | 10.4% | 9.6% |
| Age 75 to 84 | 3.9% | 4.7% | 4.5% |
| Age 85 and over | 2.1% | 2.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Lake Mathews, CA | Martinsville, VA | United States |
| White | 40.9% | 42.7% | 59.4% |
| Black | 9.2% | 44.4% | 12.2% |
| Asian | 5.9% | 0.9% | 5.6% |
| Native American | 0.5% | 0.6% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.5% | 1.1% | 0.4% |
| Two or More Races | 2.1% | 3.6% | 3.2% |
| Hispanic | 40.9% | 6.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Lake Mathews, CA | Martinsville, VA | United States |
| Married Population | 56.1% | 39.1% | 49.8% |
| Currently Married | 53.1% | 36.3% | 48.0% |
| Married but Separated | 3.0% | 2.9% | 1.8% |
| Single Population | 43.9% | 60.9% | 50.2% |
| Never Married | 33.1% | 36.9% | 33.8% |
| Divorced | 7.6% | 15.5% | 10.8% |
| Widowed | 3.2% | 8.5% | 5.6% |
| space5 | | | |
| Household Size | 3.86 | 2.31 | 2.60 |
| Households | 1,923 | 5,656 | 124,010,992 |
| Family Households | 1,677 | 3,162 | 80,755,759 |
| Married couple, w/children | 34.7% | 15.4% | 30.5% |
| Married couple, no children | 40.4% | 37.4% | 42.9% |
| Non Family Households | 246 | 2,494 | 43,255,233 |
| Single householder, w/children | 18.5% | 26.6% | 15.8% |
| Single householder, no children | 6.4% | 20.6% | 10.8% |