| | Bellport, NY | Oakland, CA | United States |
| Population | 1,957 | 437,548 | 329,725,481 |
| Female Population | 48.7% | 51.4% | 50.5% |
| Male Population | 51.4% | 48.6% | 49.5% |
| Median Age | 56.6 | 36.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,080 | 391,350 | 309,327,143 |
| Population - 2000 | 2,363 | 399,484 | 285,036,114 |
| Population - 1990 | 2,572 | 372,242 | 251,960,433 |
| Pop. 2000 to Now | -13.7% | 6.4% | 15.6% |
| Pop. 1990 to Now | -20.7% | 14.1% | 30.8% |
| space4 | | | |
| Population Density | 1,368.5 | 7,828.3 | 93.4 |
| Land Area | 1.4 | 55.9 | 3,531,905.4 |
| Water Area | 0.1 | 22.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Bellport, NY | Oakland, CA | United States |
| Age 0 to 4 | 2.1% | 6.0% | 5.9% |
| Age 5 to 9 | 2.3% | 5.2% | 6.1% |
| Age 10 to 14 | 5.1% | 5.6% | 6.6% |
| Age 15 to 17 | 4.1% | 2.9% | 3.9% |
| Age 18 to 20 | 2.8% | 2.9% | 4.0% |
| Age 21 to 24 | 2.0% | 4.2% | 5.2% |
| Age 25 to 34 | 8.5% | 19.7% | 13.8% |
| Age 35 to 44 | 7.4% | 16.3% | 12.9% |
| Age 45 to 54 | 10.7% | 12.5% | 12.6% |
| Age 55 to 59 | 13.5% | 5.8% | 6.7% |
| Age 60 to 64 | 10.1% | 5.4% | 6.3% |
| Age 65 to 74 | 21.1% | 8.3% | 9.6% |
| Age 75 to 84 | 4.4% | 3.7% | 4.5% |
| Age 85 and over | 5.9% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Bellport, NY | Oakland, CA | United States |
| White | 91.6% | 28.6% | 59.4% |
| Black | 1.1% | 21.6% | 12.2% |
| Asian | 1.0% | 15.6% | 5.6% |
| Native American | 0.0% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.5% | 0.2% |
| Other | 1.5% | 0.6% | 0.4% |
| Two or More Races | 2.7% | 5.7% | 3.2% |
| Hispanic | 2.2% | 27.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Bellport, NY | Oakland, CA | United States |
| Married Population | 53.0% | 41.1% | 49.8% |
| Currently Married | 53.0% | 39.1% | 48.0% |
| Married but Separated | 0.0% | 2.0% | 1.8% |
| Single Population | 47.0% | 58.9% | 50.2% |
| Never Married | 21.4% | 45.2% | 33.8% |
| Divorced | 16.6% | 9.3% | 10.8% |
| Widowed | 9.0% | 4.4% | 5.6% |
| space5 | | | |
| Household Size | 2.11 | 2.58 | 2.60 |
| Households | 924 | 167,307 | 124,010,992 |
| Family Households | 550 | 91,235 | 80,755,759 |
| Married couple, w/children | 22.0% | 29.5% | 30.5% |
| Married couple, no children | 58.9% | 35.9% | 42.9% |
| Non Family Households | 374 | 76,072 | 43,255,233 |
| Single householder, w/children | 8.7% | 19.2% | 15.8% |
| Single householder, no children | 10.4% | 15.5% | 10.8% |