| | Cold Spring Harbor, NY | Locust Valley, NY | United States |
| Population | 3,067 | 3,607 | 329,725,481 |
| Female Population | 48.4% | 47.0% | 50.5% |
| Male Population | 51.6% | 53.0% | 49.5% |
| Median Age | 37 | 41.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 4,952 | 3,091 | 309,327,143 |
| Population - 2000 | 4,975 | 3,521 | 285,036,114 |
| Population - 1990 | 4,789 | 3,963 | 251,960,433 |
| Pop. 2000 to Now | 1.1% | -10.1% | 15.6% |
| Pop. 1990 to Now | 5.0% | -20.1% | 30.8% |
| space4 | | | |
| Population Density | 837.3 | 3,976.9 | 93.4 |
| Land Area | 3.7 | 0.9 | 3,531,905.4 |
| Water Area | 0.2 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Cold Spring Harbor, NY | Locust Valley, NY | United States |
| Age 0 to 4 | 9.0% | 5.9% | 5.9% |
| Age 5 to 9 | 8.1% | 6.5% | 6.1% |
| Age 10 to 14 | 6.9% | 11.4% | 6.6% |
| Age 15 to 17 | 4.2% | 4.5% | 3.9% |
| Age 18 to 20 | 2.1% | 4.3% | 4.0% |
| Age 21 to 24 | 6.7% | 2.4% | 5.2% |
| Age 25 to 34 | 9.6% | 7.8% | 13.8% |
| Age 35 to 44 | 8.2% | 12.4% | 12.9% |
| Age 45 to 54 | 16.8% | 19.1% | 12.6% |
| Age 55 to 59 | 6.6% | 4.5% | 6.7% |
| Age 60 to 64 | 10.3% | 8.2% | 6.3% |
| Age 65 to 74 | 6.5% | 7.5% | 9.6% |
| Age 75 to 84 | 3.2% | 2.2% | 4.5% |
| Age 85 and over | 2.1% | 3.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Cold Spring Harbor, NY | Locust Valley, NY | United States |
| White | 83.8% | 79.3% | 59.4% |
| Black | 0.0% | 1.5% | 12.2% |
| Asian | 3.5% | 0.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 2.1% | 0.0% | 0.4% |
| Two or More Races | 5.9% | 1.1% | 3.2% |
| Hispanic | 4.8% | 17.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Cold Spring Harbor, NY | Locust Valley, NY | United States |
| Married Population | 66.3% | 62.0% | 49.8% |
| Currently Married | 64.7% | 61.4% | 48.0% |
| Married but Separated | 1.6% | 0.6% | 1.8% |
| Single Population | 33.7% | 38.0% | 50.2% |
| Never Married | 24.1% | 28.3% | 33.8% |
| Divorced | 4.2% | 6.1% | 10.8% |
| Widowed | 5.4% | 3.6% | 5.6% |
| space5 | | | |
| Household Size | 3.12 | 2.97 | 2.60 |
| Households | 958 | 1,209 | 124,010,992 |
| Family Households | 782 | 961 | 80,755,759 |
| Married couple, w/children | 61.5% | 35.5% | 30.5% |
| Married couple, no children | 33.5% | 50.1% | 42.9% |
| Non Family Households | 176 | 248 | 43,255,233 |
| Single householder, w/children | 0.0% | 9.7% | 15.8% |
| Single householder, no children | 5.0% | 4.8% | 10.8% |