| | Ketchum, ID | Gilroy, CA | United States |
| Population | 3,448 | 58,802 | 329,725,481 |
| Female Population | 51.8% | 50.2% | 50.5% |
| Male Population | 48.2% | 49.8% | 49.5% |
| Median Age | 51.3 | 35 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,704 | 49,139 | 309,327,143 |
| Population - 2000 | 3,003 | 41,464 | 285,036,114 |
| Population - 1990 | 2,523 | 31,487 | 251,960,433 |
| Pop. 2000 to Now | -3.1% | 32.2% | 15.6% |
| Pop. 1990 to Now | 15.3% | 74.1% | 30.8% |
| space4 | | | |
| Population Density | 1,075.2 | 3,569.6 | 93.4 |
| Land Area | 3.2 | 16.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Ketchum, ID | Gilroy, CA | United States |
| Age 0 to 4 | 2.1% | 6.7% | 5.9% |
| Age 5 to 9 | 1.9% | 7.4% | 6.1% |
| Age 10 to 14 | 3.7% | 9.5% | 6.6% |
| Age 15 to 17 | 4.8% | 5.2% | 3.9% |
| Age 18 to 20 | 2.5% | 4.4% | 4.0% |
| Age 21 to 24 | 1.7% | 4.8% | 5.2% |
| Age 25 to 34 | 19.6% | 12.0% | 13.8% |
| Age 35 to 44 | 6.7% | 14.2% | 12.9% |
| Age 45 to 54 | 12.3% | 13.1% | 12.6% |
| Age 55 to 59 | 13.7% | 5.9% | 6.7% |
| Age 60 to 64 | 8.7% | 5.0% | 6.3% |
| Age 65 to 74 | 15.0% | 7.1% | 9.6% |
| Age 75 to 84 | 5.7% | 3.3% | 4.5% |
| Age 85 and over | 1.8% | 1.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Ketchum, ID | Gilroy, CA | United States |
| White | 87.4% | 26.7% | 59.4% |
| Black | 1.0% | 1.4% | 12.2% |
| Asian | 0.6% | 9.7% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 1.8% | 3.6% | 3.2% |
| Hispanic | 9.1% | 58.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Ketchum, ID | Gilroy, CA | United States |
| Married Population | 58.8% | 50.6% | 49.8% |
| Currently Married | 58.8% | 48.6% | 48.0% |
| Married but Separated | 0.0% | 2.1% | 1.8% |
| Single Population | 41.2% | 49.4% | 50.2% |
| Never Married | 25.5% | 35.0% | 33.8% |
| Divorced | 11.2% | 10.2% | 10.8% |
| Widowed | 4.5% | 4.2% | 5.6% |
| space5 | | | |
| Household Size | 2.20 | 3.43 | 2.60 |
| Households | 1,567 | 17,023 | 124,010,992 |
| Family Households | 960 | 13,647 | 80,755,759 |
| Married couple, w/children | 18.1% | 39.5% | 30.5% |
| Married couple, no children | 70.9% | 31.7% | 42.9% |
| Non Family Households | 607 | 3,376 | 43,255,233 |
| Single householder, w/children | 5.7% | 17.6% | 15.8% |
| Single householder, no children | 5.2% | 11.2% | 10.8% |