| | Plymouth, CA | Parma, ID | United States |
| Population | 1,138 | 1,776 | 329,725,481 |
| Female Population | 41.5% | 51.4% | 50.5% |
| Male Population | 58.5% | 48.7% | 49.5% |
| Median Age | 41.7 | 39.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 986 | 1,976 | 309,327,143 |
| Population - 2000 | 980 | 1,771 | 285,036,114 |
| Population - 1990 | 811 | 1,597 | 251,960,433 |
| Pop. 2000 to Now | 6.4% | 20.2% | 15.6% |
| Pop. 1990 to Now | 28.6% | 33.3% | 30.8% |
| space4 | | | |
| Population Density | 430.6 | 1,642.9 | 93.4 |
| Land Area | 2.6 | 1.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Plymouth, CA | Parma, ID | United States |
| Age 0 to 4 | 3.4% | 6.6% | 5.9% |
| Age 5 to 9 | 3.1% | 7.9% | 6.1% |
| Age 10 to 14 | 4.7% | 9.8% | 6.6% |
| Age 15 to 17 | 3.5% | 2.2% | 3.9% |
| Age 18 to 20 | 9.1% | 2.8% | 4.0% |
| Age 21 to 24 | 4.2% | 3.5% | 5.2% |
| Age 25 to 34 | 12.9% | 12.1% | 13.8% |
| Age 35 to 44 | 14.5% | 11.6% | 12.9% |
| Age 45 to 54 | 16.9% | 15.4% | 12.6% |
| Age 55 to 59 | 2.9% | 2.3% | 6.7% |
| Age 60 to 64 | 9.0% | 5.8% | 6.3% |
| Age 65 to 74 | 10.2% | 12.2% | 9.6% |
| Age 75 to 84 | 4.5% | 6.3% | 4.5% |
| Age 85 and over | 1.1% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Plymouth, CA | Parma, ID | United States |
| White | 67.8% | 74.2% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 1.0% | 1.6% | 5.6% |
| Native American | 0.9% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.1% | 1.1% | 3.2% |
| Hispanic | 27.3% | 22.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Plymouth, CA | Parma, ID | United States |
| Married Population | 50.1% | 54.7% | 49.8% |
| Currently Married | 49.5% | 53.5% | 48.0% |
| Married but Separated | 0.6% | 1.2% | 1.8% |
| Single Population | 49.9% | 45.3% | 50.2% |
| Never Married | 34.7% | 22.5% | 33.8% |
| Divorced | 9.2% | 17.6% | 10.8% |
| Widowed | 6.0% | 5.1% | 5.6% |
| space5 | | | |
| Household Size | 2.46 | 2.58 | 2.60 |
| Households | 462 | 680 | 124,010,992 |
| Family Households | 318 | 459 | 80,755,759 |
| Married couple, w/children | 32.7% | 32.7% | 30.5% |
| Married couple, no children | 40.3% | 41.2% | 42.9% |
| Non Family Households | 144 | 221 | 43,255,233 |
| Single householder, w/children | 20.1% | 19.2% | 15.8% |
| Single householder, no children | 6.9% | 7.0% | 10.8% |