| | San Lucas, CA | Greenfield, CA | United States |
| Population | 358 | 18,833 | 329,725,481 |
| Female Population | 50.8% | 49.9% | 50.5% |
| Male Population | 49.2% | 50.1% | 49.5% |
| Median Age | 21.7 | 27.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 191 | 16,373 | 309,327,143 |
| Population - 2000 | 419 | 12,583 | 285,036,114 |
| Population - 1990 | 107 | 7,464 | 251,960,433 |
| Pop. 2000 to Now | -17.2% | 40.2% | 15.6% |
| Pop. 1990 to Now | 224.3% | 136.4% | 30.8% |
| space4 | | | |
| Population Density | 908.6 | 8,817.0 | 93.4 |
| Land Area | 0.4 | 2.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | San Lucas, CA | Greenfield, CA | United States |
| Age 0 to 4 | 8.9% | 10.5% | 5.9% |
| Age 5 to 9 | 12.8% | 9.4% | 6.1% |
| Age 10 to 14 | 16.8% | 10.5% | 6.6% |
| Age 15 to 17 | 6.4% | 5.7% | 3.9% |
| Age 18 to 20 | 3.9% | 4.7% | 4.0% |
| Age 21 to 24 | 4.7% | 5.4% | 5.2% |
| Age 25 to 34 | 14.0% | 14.4% | 13.8% |
| Age 35 to 44 | 11.5% | 14.3% | 12.9% |
| Age 45 to 54 | 7.8% | 9.8% | 12.6% |
| Age 55 to 59 | 5.6% | 5.0% | 6.7% |
| Age 60 to 64 | 3.9% | 4.1% | 6.3% |
| Age 65 to 74 | 2.2% | 5.1% | 9.6% |
| Age 75 to 84 | 1.4% | 1.2% | 4.5% |
| Age 85 and over | 0.0% | 0.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | San Lucas, CA | Greenfield, CA | United States |
| White | 7.3% | 3.3% | 59.4% |
| Black | 0.0% | 0.8% | 12.2% |
| Asian | 0.0% | 1.1% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 0.0% | 1.0% | 3.2% |
| Hispanic | 92.7% | 93.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | San Lucas, CA | Greenfield, CA | United States |
| Married Population | 48.2% | 52.3% | 49.8% |
| Currently Married | 45.5% | 50.5% | 48.0% |
| Married but Separated | 2.7% | 1.9% | 1.8% |
| Single Population | 51.8% | 47.7% | 50.2% |
| Never Married | 42.7% | 42.6% | 33.8% |
| Divorced | 4.5% | 2.5% | 10.8% |
| Widowed | 4.5% | 2.6% | 5.6% |
| space5 | | | |
| Household Size | 5.42 | 4.58 | 2.60 |
| Households | 66 | 4,096 | 124,010,992 |
| Family Households | 64 | 3,721 | 80,755,759 |
| Married couple, w/children | 45.3% | 46.2% | 30.5% |
| Married couple, no children | 0.0% | 21.8% | 42.9% |
| Non Family Households | 2 | 375 | 43,255,233 |
| Single householder, w/children | 42.2% | 23.5% | 15.8% |
| Single householder, no children | 12.5% | 8.4% | 10.8% |