| | Altadena, CA | Yorba Linda, CA | United States |
| Population | 43,384 | 68,319 | 329,725,481 |
| Female Population | 53.0% | 51.0% | 50.5% |
| Male Population | 47.0% | 49.0% | 49.5% |
| Median Age | 43.9 | 44.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 45,446 | 64,341 | 309,327,143 |
| Population - 2000 | 42,610 | 58,918 | 285,036,114 |
| Population - 1990 | 42,658 | 52,422 | 251,960,433 |
| Pop. 2000 to Now | 4.8% | 15.5% | 15.6% |
| Pop. 1990 to Now | 4.6% | 29.8% | 30.8% |
| space4 | | | |
| Population Density | 5,124.5 | 3,443.2 | 93.4 |
| Land Area | 8.5 | 19.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Altadena, CA | Yorba Linda, CA | United States |
| Age 0 to 4 | 5.4% | 4.7% | 5.9% |
| Age 5 to 9 | 5.5% | 7.2% | 6.1% |
| Age 10 to 14 | 5.8% | 6.8% | 6.6% |
| Age 15 to 17 | 3.5% | 4.3% | 3.9% |
| Age 18 to 20 | 2.6% | 3.2% | 4.0% |
| Age 21 to 24 | 3.4% | 3.5% | 5.2% |
| Age 25 to 34 | 11.8% | 9.8% | 13.8% |
| Age 35 to 44 | 13.0% | 11.5% | 12.9% |
| Age 45 to 54 | 14.7% | 15.5% | 12.6% |
| Age 55 to 59 | 8.2% | 7.4% | 6.7% |
| Age 60 to 64 | 6.8% | 7.7% | 6.3% |
| Age 65 to 74 | 10.5% | 11.0% | 9.6% |
| Age 75 to 84 | 6.1% | 5.4% | 4.5% |
| Age 85 and over | 2.7% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Altadena, CA | Yorba Linda, CA | United States |
| White | 39.5% | 54.4% | 59.4% |
| Black | 19.8% | 1.2% | 12.2% |
| Asian | 5.3% | 21.9% | 5.6% |
| Native American | 0.1% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.2% | 0.2% |
| Other | 0.4% | 0.5% | 0.4% |
| Two or More Races | 5.6% | 3.6% | 3.2% |
| Hispanic | 29.3% | 18.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Altadena, CA | Yorba Linda, CA | United States |
| Married Population | 49.8% | 62.5% | 49.8% |
| Currently Married | 48.0% | 61.8% | 48.0% |
| Married but Separated | 1.8% | 0.7% | 1.8% |
| Single Population | 50.2% | 37.5% | 50.2% |
| Never Married | 32.2% | 25.5% | 33.8% |
| Divorced | 11.3% | 7.4% | 10.8% |
| Widowed | 6.6% | 4.6% | 5.6% |
| space5 | | | |
| Household Size | 2.89 | 2.97 | 2.60 |
| Households | 14,789 | 22,920 | 124,010,992 |
| Family Households | 10,753 | 18,632 | 80,755,759 |
| Married couple, w/children | 28.9% | 35.7% | 30.5% |
| Married couple, no children | 42.0% | 49.8% | 42.9% |
| Non Family Households | 4,036 | 4,288 | 43,255,233 |
| Single householder, w/children | 14.4% | 6.9% | 15.8% |
| Single householder, no children | 14.7% | 7.6% | 10.8% |