| | Castleford, ID | Lapwai, ID | United States |
| Population | 135 | 1,486 | 329,725,481 |
| Female Population | 43.7% | 53.4% | 50.5% |
| Male Population | 56.3% | 46.6% | 49.5% |
| Median Age | 37.4 | 31.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 226 | 1,129 | 309,327,143 |
| Population - 2000 | 277 | 1,134 | 285,036,114 |
| Population - 1990 | 179 | 932 | 251,960,433 |
| Pop. 2000 to Now | -9.4% | 1.6% | 15.6% |
| Pop. 1990 to Now | 40.2% | 23.6% | 30.8% |
| space4 | | | |
| Population Density | 1,406.3 | 1,965.6 | 93.4 |
| Land Area | 0.1 | 0.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Castleford, ID | Lapwai, ID | United States |
| Age 0 to 4 | 16.3% | 7.9% | 5.9% |
| Age 5 to 9 | 9.6% | 8.6% | 6.1% |
| Age 10 to 14 | 4.4% | 10.8% | 6.6% |
| Age 15 to 17 | 1.5% | 6.1% | 3.9% |
| Age 18 to 20 | 0.7% | 5.2% | 4.0% |
| Age 21 to 24 | 0.7% | 2.4% | 5.2% |
| Age 25 to 34 | 14.8% | 18.5% | 13.8% |
| Age 35 to 44 | 10.4% | 12.0% | 12.9% |
| Age 45 to 54 | 7.4% | 6.1% | 12.6% |
| Age 55 to 59 | 8.9% | 4.2% | 6.7% |
| Age 60 to 64 | 3.0% | 7.6% | 6.3% |
| Age 65 to 74 | 20.7% | 6.3% | 9.6% |
| Age 75 to 84 | 1.5% | 2.8% | 4.5% |
| Age 85 and over | 0.0% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Castleford, ID | Lapwai, ID | United States |
| White | 51.1% | 13.3% | 59.4% |
| Black | 0.0% | 0.2% | 12.2% |
| Asian | 0.0% | 1.7% | 5.6% |
| Native American | 0.0% | 72.9% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.3% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 0.0% | 6.7% | 3.2% |
| Hispanic | 48.9% | 4.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Castleford, ID | Lapwai, ID | United States |
| Married Population | 67.0% | 38.4% | 49.8% |
| Currently Married | 60.6% | 36.3% | 48.0% |
| Married but Separated | 6.4% | 2.1% | 1.8% |
| Single Population | 33.0% | 61.6% | 50.2% |
| Never Married | 13.8% | 45.5% | 33.8% |
| Divorced | 6.4% | 10.0% | 10.8% |
| Widowed | 12.8% | 6.1% | 5.6% |
| space5 | | | |
| Household Size | 2.60 | 3.50 | 2.60 |
| Households | 52 | 421 | 124,010,992 |
| Family Households | 36 | 356 | 80,755,759 |
| Married couple, w/children | 13.9% | 33.1% | 30.5% |
| Married couple, no children | 61.1% | 19.7% | 42.9% |
| Non Family Households | 16 | 65 | 43,255,233 |
| Single householder, w/children | 16.7% | 32.3% | 15.8% |
| Single householder, no children | 8.3% | 14.9% | 10.8% |