| | Eagle, ID | Simi Valley, CA | United States |
| Population | 29,665 | 126,809 | 329,725,481 |
| Female Population | 51.0% | 51.0% | 50.5% |
| Male Population | 49.0% | 49.1% | 49.5% |
| Median Age | 45.5 | 41 | 38.4 |
| space3 | | | |
| Population - 2010 | 20,012 | 124,424 | 309,327,143 |
| Population - 2000 | 11,085 | 111,351 | 285,036,114 |
| Population - 1990 | 3,327 | 100,217 | 251,960,433 |
| Pop. 2000 to Now | 186.0% | 12.4% | 15.6% |
| Pop. 1990 to Now | 852.8% | 24.9% | 30.8% |
| space4 | | | |
| Population Density | 974.5 | 3,054.0 | 93.4 |
| Land Area | 30.4 | 41.5 | 3,531,905.4 |
| Water Area | 0.5 | 0.7 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Eagle, ID | Simi Valley, CA | United States |
| Age 0 to 4 | 5.3% | 5.2% | 5.9% |
| Age 5 to 9 | 5.6% | 4.8% | 6.1% |
| Age 10 to 14 | 8.5% | 6.6% | 6.6% |
| Age 15 to 17 | 5.3% | 4.2% | 3.9% |
| Age 18 to 20 | 2.8% | 3.8% | 4.0% |
| Age 21 to 24 | 1.9% | 4.6% | 5.2% |
| Age 25 to 34 | 7.7% | 13.3% | 13.8% |
| Age 35 to 44 | 12.2% | 12.5% | 12.9% |
| Age 45 to 54 | 13.3% | 14.8% | 12.6% |
| Age 55 to 59 | 8.4% | 7.7% | 6.7% |
| Age 60 to 64 | 7.0% | 6.7% | 6.3% |
| Age 65 to 74 | 14.2% | 9.2% | 9.6% |
| Age 75 to 84 | 6.3% | 4.5% | 4.5% |
| Age 85 and over | 1.5% | 2.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Eagle, ID | Simi Valley, CA | United States |
| White | 85.6% | 57.6% | 59.4% |
| Black | 0.6% | 1.3% | 12.2% |
| Asian | 1.7% | 11.1% | 5.6% |
| Native American | 0.4% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.4% | 0.1% | 0.2% |
| Other | 0.2% | 0.1% | 0.4% |
| Two or More Races | 3.0% | 3.8% | 3.2% |
| Hispanic | 8.1% | 25.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Eagle, ID | Simi Valley, CA | United States |
| Married Population | 67.2% | 50.5% | 49.8% |
| Currently Married | 67.0% | 49.1% | 48.0% |
| Married but Separated | 0.1% | 1.4% | 1.8% |
| Single Population | 32.8% | 49.5% | 50.2% |
| Never Married | 20.3% | 33.6% | 33.8% |
| Divorced | 7.7% | 10.1% | 10.8% |
| Widowed | 4.9% | 5.9% | 5.6% |
| space5 | | | |
| Household Size | 2.64 | 2.87 | 2.60 |
| Households | 11,221 | 43,893 | 124,010,992 |
| Family Households | 8,869 | 30,965 | 80,755,759 |
| Married couple, w/children | 32.3% | 32.3% | 30.5% |
| Married couple, no children | 54.8% | 43.9% | 42.9% |
| Non Family Households | 2,352 | 12,928 | 43,255,233 |
| Single householder, w/children | 9.4% | 10.9% | 15.8% |
| Single householder, no children | 3.6% | 12.8% | 10.8% |