| | Round Lake, NY | Endwell, NY | United States |
| Population | 832 | 11,795 | 329,725,481 |
| Female Population | 50.5% | 51.6% | 50.5% |
| Male Population | 49.5% | 48.4% | 49.5% |
| Median Age | 46 | 44.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 624 | 11,691 | 309,327,143 |
| Population - 2000 | 604 | 11,706 | 285,036,114 |
| Population - 1990 | 765 | 12,602 | 251,960,433 |
| Pop. 2000 to Now | 31.3% | -5.8% | 15.6% |
| Pop. 1990 to Now | 3.7% | -12.5% | 30.8% |
| space4 | | | |
| Population Density | 741.5 | 3,150.4 | 93.4 |
| Land Area | 1.1 | 3.7 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Round Lake, NY | Endwell, NY | United States |
| Age 0 to 4 | 5.6% | 5.7% | 5.9% |
| Age 5 to 9 | 4.0% | 6.2% | 6.1% |
| Age 10 to 14 | 7.8% | 6.6% | 6.6% |
| Age 15 to 17 | 1.3% | 3.1% | 3.9% |
| Age 18 to 20 | 1.4% | 2.5% | 4.0% |
| Age 21 to 24 | 3.0% | 5.9% | 5.2% |
| Age 25 to 34 | 11.9% | 8.4% | 13.8% |
| Age 35 to 44 | 13.3% | 12.4% | 12.9% |
| Age 45 to 54 | 14.9% | 12.3% | 12.6% |
| Age 55 to 59 | 12.3% | 7.8% | 6.7% |
| Age 60 to 64 | 4.4% | 7.2% | 6.3% |
| Age 65 to 74 | 14.4% | 12.3% | 9.6% |
| Age 75 to 84 | 4.9% | 6.3% | 4.5% |
| Age 85 and over | 0.6% | 3.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Round Lake, NY | Endwell, NY | United States |
| White | 92.9% | 87.8% | 59.4% |
| Black | 2.9% | 1.0% | 12.2% |
| Asian | 1.0% | 4.5% | 5.6% |
| Native American | 0.0% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.1% | 1.2% | 3.2% |
| Hispanic | 2.2% | 5.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Round Lake, NY | Endwell, NY | United States |
| Married Population | 64.2% | 55.6% | 49.8% |
| Currently Married | 61.1% | 54.0% | 48.0% |
| Married but Separated | 3.1% | 1.6% | 1.8% |
| Single Population | 35.8% | 44.4% | 50.2% |
| Never Married | 18.8% | 27.6% | 33.8% |
| Divorced | 14.0% | 11.4% | 10.8% |
| Widowed | 3.1% | 5.4% | 5.6% |
| space5 | | | |
| Household Size | 2.34 | 2.30 | 2.60 |
| Households | 355 | 5,119 | 124,010,992 |
| Family Households | 221 | 3,100 | 80,755,759 |
| Married couple, w/children | 38.9% | 27.5% | 30.5% |
| Married couple, no children | 53.4% | 53.7% | 42.9% |
| Non Family Households | 134 | 2,019 | 43,255,233 |
| Single householder, w/children | 2.7% | 12.2% | 15.8% |
| Single householder, no children | 5.0% | 6.6% | 10.8% |