| | Gridley, CA | Folsom, CA | United States |
| Population | 7,510 | 79,201 | 329,725,481 |
| Female Population | 50.8% | 49.1% | 50.5% |
| Male Population | 49.2% | 50.9% | 49.5% |
| Median Age | 31.4 | 40.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 6,633 | 72,133 | 309,327,143 |
| Population - 2000 | 5,382 | 51,884 | 285,036,114 |
| Population - 1990 | 4,631 | 29,802 | 251,960,433 |
| Pop. 2000 to Now | 37.4% | 59.4% | 15.6% |
| Pop. 1990 to Now | 59.7% | 177.6% | 30.8% |
| space4 | | | |
| Population Density | 3,603.7 | 2,848.3 | 93.4 |
| Land Area | 2.1 | 27.8 | 3,531,905.4 |
| Water Area | 0.0 | 2.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Gridley, CA | Folsom, CA | United States |
| Age 0 to 4 | 6.6% | 5.3% | 5.9% |
| Age 5 to 9 | 12.7% | 6.3% | 6.1% |
| Age 10 to 14 | 10.7% | 7.8% | 6.6% |
| Age 15 to 17 | 3.7% | 4.5% | 3.9% |
| Age 18 to 20 | 3.1% | 2.8% | 4.0% |
| Age 21 to 24 | 5.2% | 4.1% | 5.2% |
| Age 25 to 34 | 11.5% | 11.3% | 13.8% |
| Age 35 to 44 | 13.5% | 15.8% | 12.9% |
| Age 45 to 54 | 10.7% | 17.6% | 12.6% |
| Age 55 to 59 | 6.3% | 6.4% | 6.7% |
| Age 60 to 64 | 5.0% | 5.6% | 6.3% |
| Age 65 to 74 | 6.0% | 7.4% | 9.6% |
| Age 75 to 84 | 3.1% | 3.6% | 4.5% |
| Age 85 and over | 1.7% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Gridley, CA | Folsom, CA | United States |
| White | 56.5% | 55.9% | 59.4% |
| Black | 0.1% | 4.5% | 12.2% |
| Asian | 1.1% | 17.7% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.3% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 4.0% | 5.0% | 3.2% |
| Hispanic | 38.2% | 15.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Gridley, CA | Folsom, CA | United States |
| Married Population | 57.0% | 57.2% | 49.8% |
| Currently Married | 54.1% | 55.9% | 48.0% |
| Married but Separated | 2.9% | 1.4% | 1.8% |
| Single Population | 43.0% | 42.8% | 50.2% |
| Never Married | 26.9% | 28.1% | 33.8% |
| Divorced | 11.7% | 10.7% | 10.8% |
| Widowed | 4.4% | 3.9% | 5.6% |
| space5 | | | |
| Household Size | 3.01 | 2.70 | 2.60 |
| Households | 2,460 | 27,275 | 124,010,992 |
| Family Households | 1,838 | 19,906 | 80,755,759 |
| Married couple, w/children | 36.3% | 43.7% | 30.5% |
| Married couple, no children | 34.3% | 40.0% | 42.9% |
| Non Family Households | 622 | 7,369 | 43,255,233 |
| Single householder, w/children | 19.0% | 8.8% | 15.8% |
| Single householder, no children | 10.3% | 7.5% | 10.8% |