| | Castroville, TX | Buffalo, WY | United States |
| Population | 2,939 | 4,389 | 329,725,481 |
| Female Population | 56.0% | 45.6% | 50.5% |
| Male Population | 44.0% | 54.4% | 49.5% |
| Median Age | 38.5 | 49.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,791 | 4,592 | 309,327,143 |
| Population - 2000 | 2,664 | 3,900 | 285,036,114 |
| Population - 1990 | 2,159 | 3,302 | 251,960,433 |
| Pop. 2000 to Now | 20.1% | 19.5% | 15.6% |
| Pop. 1990 to Now | 48.2% | 41.1% | 30.8% |
| space4 | | | |
| Population Density | 1,071.9 | 980.8 | 93.4 |
| Land Area | 2.7 | 4.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Castroville, TX | Buffalo, WY | United States |
| Age 0 to 4 | 6.1% | 6.5% | 5.9% |
| Age 5 to 9 | 6.0% | 5.8% | 6.1% |
| Age 10 to 14 | 6.7% | 5.1% | 6.6% |
| Age 15 to 17 | 4.4% | 1.9% | 3.9% |
| Age 18 to 20 | 3.0% | 3.0% | 4.0% |
| Age 21 to 24 | 7.8% | 4.7% | 5.2% |
| Age 25 to 34 | 12.2% | 7.7% | 13.8% |
| Age 35 to 44 | 6.8% | 9.7% | 12.9% |
| Age 45 to 54 | 14.0% | 12.6% | 12.6% |
| Age 55 to 59 | 7.4% | 6.0% | 6.7% |
| Age 60 to 64 | 6.3% | 7.1% | 6.3% |
| Age 65 to 74 | 7.9% | 17.4% | 9.6% |
| Age 75 to 84 | 8.3% | 8.6% | 4.5% |
| Age 85 and over | 3.0% | 3.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Castroville, TX | Buffalo, WY | United States |
| White | 47.1% | 88.5% | 59.4% |
| Black | 0.6% | 1.4% | 12.2% |
| Asian | 1.5% | 1.1% | 5.6% |
| Native American | 0.0% | 1.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 3.8% | 2.8% | 3.2% |
| Hispanic | 47.1% | 4.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Castroville, TX | Buffalo, WY | United States |
| Married Population | 56.6% | 58.4% | 49.8% |
| Currently Married | 55.0% | 57.0% | 48.0% |
| Married but Separated | 1.6% | 1.4% | 1.8% |
| Single Population | 43.4% | 41.6% | 50.2% |
| Never Married | 26.1% | 15.2% | 33.8% |
| Divorced | 10.2% | 17.2% | 10.8% |
| Widowed | 7.0% | 9.2% | 5.6% |
| space5 | | | |
| Household Size | 2.70 | 1.93 | 2.60 |
| Households | 1,057 | 2,224 | 124,010,992 |
| Family Households | 794 | 1,095 | 80,755,759 |
| Married couple, w/children | 27.8% | 25.3% | 30.5% |
| Married couple, no children | 46.3% | 65.5% | 42.9% |
| Non Family Households | 263 | 1,129 | 43,255,233 |
| Single householder, w/children | 12.0% | 8.0% | 15.8% |
| Single householder, no children | 13.9% | 1.2% | 10.8% |