| | Waterloo, AL | Ava, MO | United States |
| Population | 118 | 2,864 | 329,725,481 |
| Female Population | 50.0% | 47.1% | 50.5% |
| Male Population | 50.0% | 52.9% | 49.5% |
| Median Age | 57.4 | 35.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 203 | 2,982 | 309,327,143 |
| Population - 2000 | 208 | 3,021 | 285,036,114 |
| Population - 1990 | 250 | 2,938 | 251,960,433 |
| Pop. 2000 to Now | -4.3% | -3.8% | 15.6% |
| Pop. 1990 to Now | -20.4% | -1.1% | 30.8% |
| space4 | | | |
| Population Density | 157.8 | 868.1 | 93.4 |
| Land Area | 0.7 | 3.3 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Waterloo, AL | Ava, MO | United States |
| Age 0 to 4 | 5.9% | 6.3% | 5.9% |
| Age 5 to 9 | 0.8% | 10.6% | 6.1% |
| Age 10 to 14 | 4.2% | 7.1% | 6.6% |
| Age 15 to 17 | 3.4% | 4.1% | 3.9% |
| Age 18 to 20 | 0.0% | 5.1% | 4.0% |
| Age 21 to 24 | 2.5% | 6.4% | 5.2% |
| Age 25 to 34 | 5.9% | 9.5% | 13.8% |
| Age 35 to 44 | 0.8% | 13.8% | 12.9% |
| Age 45 to 54 | 24.6% | 10.4% | 12.6% |
| Age 55 to 59 | 11.0% | 5.0% | 6.7% |
| Age 60 to 64 | 5.1% | 1.9% | 6.3% |
| Age 65 to 74 | 23.7% | 14.8% | 9.6% |
| Age 75 to 84 | 6.8% | 3.0% | 4.5% |
| Age 85 and over | 5.1% | 2.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Waterloo, AL | Ava, MO | United States |
| White | 96.6% | 99.5% | 59.4% |
| Black | 0.0% | 0.4% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.7% | 0.1% | 3.2% |
| Hispanic | 1.7% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Waterloo, AL | Ava, MO | United States |
| Married Population | 51.4% | 47.3% | 49.8% |
| Currently Married | 51.4% | 44.4% | 48.0% |
| Married but Separated | 0.0% | 3.0% | 1.8% |
| Single Population | 48.6% | 52.7% | 50.2% |
| Never Married | 16.2% | 28.3% | 33.8% |
| Divorced | 21.0% | 19.7% | 10.8% |
| Widowed | 11.4% | 4.6% | 5.6% |
| space5 | | | |
| Household Size | 1.97 | 2.61 | 2.60 |
| Households | 60 | 1,056 | 124,010,992 |
| Family Households | 30 | 618 | 80,755,759 |
| Married couple, w/children | 10.0% | 45.3% | 30.5% |
| Married couple, no children | 56.7% | 30.9% | 42.9% |
| Non Family Households | 30 | 438 | 43,255,233 |
| Single householder, w/children | 16.7% | 13.4% | 15.8% |
| Single householder, no children | 16.7% | 10.4% | 10.8% |