| | Somersworth, NH | Oceanside, CA | United States |
| Population | 11,964 | 174,461 | 329,725,481 |
| Female Population | 48.8% | 50.1% | 50.5% |
| Male Population | 51.3% | 49.9% | 49.5% |
| Median Age | 39.7 | 37.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,764 | 167,944 | 309,327,143 |
| Population - 2000 | 11,477 | 161,029 | 285,036,114 |
| Population - 1990 | 11,249 | 128,398 | 251,960,433 |
| Pop. 2000 to Now | 7.1% | 8.5% | 15.6% |
| Pop. 1990 to Now | 9.2% | 36.0% | 30.8% |
| space4 | | | |
| Population Density | 1,220.7 | 4,230.0 | 93.4 |
| Land Area | 9.8 | 41.2 | 3,531,905.4 |
| Water Area | 0.2 | 0.9 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Somersworth, NH | Oceanside, CA | United States |
| Age 0 to 4 | 2.6% | 6.0% | 5.9% |
| Age 5 to 9 | 3.9% | 5.8% | 6.1% |
| Age 10 to 14 | 8.3% | 6.6% | 6.6% |
| Age 15 to 17 | 5.0% | 3.2% | 3.9% |
| Age 18 to 20 | 3.1% | 3.6% | 4.0% |
| Age 21 to 24 | 2.8% | 5.8% | 5.2% |
| Age 25 to 34 | 17.4% | 16.0% | 13.8% |
| Age 35 to 44 | 13.2% | 13.1% | 12.9% |
| Age 45 to 54 | 14.9% | 11.8% | 12.6% |
| Age 55 to 59 | 7.4% | 6.6% | 6.7% |
| Age 60 to 64 | 7.3% | 6.6% | 6.3% |
| Age 65 to 74 | 9.6% | 8.5% | 9.6% |
| Age 75 to 84 | 3.9% | 4.5% | 4.5% |
| Age 85 and over | 0.7% | 1.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Somersworth, NH | Oceanside, CA | United States |
| White | 85.5% | 44.2% | 59.4% |
| Black | 1.7% | 4.4% | 12.2% |
| Asian | 4.7% | 7.5% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.5% | 0.2% |
| Other | 0.0% | 0.4% | 0.4% |
| Two or More Races | 3.5% | 4.9% | 3.2% |
| Hispanic | 4.4% | 37.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Somersworth, NH | Oceanside, CA | United States |
| Married Population | 47.2% | 51.3% | 49.8% |
| Currently Married | 46.9% | 49.7% | 48.0% |
| Married but Separated | 0.2% | 1.6% | 1.8% |
| Single Population | 52.8% | 48.7% | 50.2% |
| Never Married | 33.1% | 32.7% | 33.8% |
| Divorced | 16.1% | 11.1% | 10.8% |
| Widowed | 3.6% | 4.9% | 5.6% |
| space5 | | | |
| Household Size | 2.33 | 2.86 | 2.60 |
| Households | 5,137 | 60,838 | 124,010,992 |
| Family Households | 3,149 | 41,750 | 80,755,759 |
| Married couple, w/children | 32.1% | 30.9% | 30.5% |
| Married couple, no children | 40.8% | 44.9% | 42.9% |
| Non Family Households | 1,988 | 19,088 | 43,255,233 |
| Single householder, w/children | 17.2% | 13.7% | 15.8% |
| Single householder, no children | 9.9% | 10.5% | 10.8% |