| | National City, CA | La Mesa, CA | United States |
| Population | 56,846 | 61,040 | 329,725,481 |
| Female Population | 52.2% | 53.3% | 50.5% |
| Male Population | 47.8% | 46.7% | 49.5% |
| Median Age | 36.8 | 36 | 38.4 |
| space3 | | | |
| Population - 2010 | 58,603 | 57,347 | 309,327,143 |
| Population - 2000 | 54,260 | 54,749 | 285,036,114 |
| Population - 1990 | 54,249 | 52,931 | 251,960,433 |
| Pop. 2000 to Now | 12.3% | 9.1% | 15.6% |
| Pop. 1990 to Now | 12.3% | 12.8% | 30.8% |
| space4 | | | |
| Population Density | 7,795.7 | 6,712.1 | 93.4 |
| Land Area | 7.3 | 9.1 | 3,531,905.4 |
| Water Area | 1.8 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | National City, CA | La Mesa, CA | United States |
| Age 0 to 4 | 5.3% | 7.4% | 5.9% |
| Age 5 to 9 | 5.6% | 5.0% | 6.1% |
| Age 10 to 14 | 7.3% | 5.4% | 6.6% |
| Age 15 to 17 | 3.7% | 2.6% | 3.9% |
| Age 18 to 20 | 4.4% | 2.8% | 4.0% |
| Age 21 to 24 | 5.6% | 6.3% | 5.2% |
| Age 25 to 34 | 15.8% | 18.6% | 13.8% |
| Age 35 to 44 | 12.5% | 14.3% | 12.9% |
| Age 45 to 54 | 12.1% | 11.6% | 12.6% |
| Age 55 to 59 | 6.6% | 5.0% | 6.7% |
| Age 60 to 64 | 5.9% | 6.3% | 6.3% |
| Age 65 to 74 | 8.3% | 8.3% | 9.6% |
| Age 75 to 84 | 4.1% | 3.8% | 4.5% |
| Age 85 and over | 2.8% | 2.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | National City, CA | La Mesa, CA | United States |
| White | 10.4% | 54.4% | 59.4% |
| Black | 4.1% | 7.3% | 12.2% |
| Asian | 17.1% | 6.6% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.7% | 0.3% | 0.2% |
| Other | 0.3% | 0.2% | 0.4% |
| Two or More Races | 2.2% | 5.3% | 3.2% |
| Hispanic | 65.3% | 25.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | National City, CA | La Mesa, CA | United States |
| Married Population | 45.7% | 43.9% | 49.8% |
| Currently Married | 42.9% | 42.3% | 48.0% |
| Married but Separated | 2.8% | 1.7% | 1.8% |
| Single Population | 54.3% | 56.1% | 50.2% |
| Never Married | 38.1% | 37.7% | 33.8% |
| Divorced | 9.9% | 13.4% | 10.8% |
| Widowed | 6.3% | 5.1% | 5.6% |
| space5 | | | |
| Household Size | 3.16 | 2.46 | 2.60 |
| Households | 17,488 | 24,475 | 124,010,992 |
| Family Households | 12,650 | 14,005 | 80,755,759 |
| Married couple, w/children | 30.3% | 30.7% | 30.5% |
| Married couple, no children | 30.2% | 39.0% | 42.9% |
| Non Family Households | 4,838 | 10,470 | 43,255,233 |
| Single householder, w/children | 21.4% | 16.5% | 15.8% |
| Single householder, no children | 18.1% | 13.8% | 10.8% |