| | Johnson City, TX | Harper, TX | United States |
| Population | 1,629 | 1,203 | 329,725,481 |
| Female Population | 53.8% | 49.4% | 50.5% |
| Male Population | 46.2% | 50.6% | 49.5% |
| Median Age | 39.9 | 34.4 | 38.4 |
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| Population - 2010 | 1,657 | 1,042 | 309,327,143 |
| Population - 2000 | 1,191 | 1,006 | 285,036,114 |
| Population - 1990 | 932 | 637 | 251,960,433 |
| Pop. 2000 to Now | 84.9% | -3.5% | 15.6% |
| Pop. 1990 to Now | 136.3% | 52.4% | 30.8% |
| space4 | | | |
| Population Density | 902.0 | 21.3 | 93.4 |
| Land Area | 1.8 | 56.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Johnson City, TX | Harper, TX | United States |
| Age 0 to 4 | 6.7% | 3.0% | 5.9% |
| Age 5 to 9 | 4.3% | 12.9% | 6.1% |
| Age 10 to 14 | 6.2% | 11.3% | 6.6% |
| Age 15 to 17 | 6.4% | 4.7% | 3.9% |
| Age 18 to 20 | 4.5% | 3.8% | 4.0% |
| Age 21 to 24 | 4.8% | 0.7% | 5.2% |
| Age 25 to 34 | 13.4% | 15.8% | 13.8% |
| Age 35 to 44 | 8.8% | 9.1% | 12.9% |
| Age 45 to 54 | 18.6% | 6.9% | 12.6% |
| Age 55 to 59 | 6.3% | 8.0% | 6.7% |
| Age 60 to 64 | 4.4% | 9.1% | 6.3% |
| Age 65 to 74 | 10.9% | 7.8% | 9.6% |
| Age 75 to 84 | 3.1% | 2.1% | 4.5% |
| Age 85 and over | 1.5% | 4.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Johnson City, TX | Harper, TX | United States |
| White | 66.2% | 85.5% | 59.4% |
| Black | 0.1% | 0.0% | 12.2% |
| Asian | 0.5% | 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 | 1.2% | 0.5% | 3.2% |
| Hispanic | 32.0% | 14.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Johnson City, TX | Harper, TX | United States |
| Married Population | 41.2% | 63.6% | 49.8% |
| Currently Married | 38.3% | 62.3% | 48.0% |
| Married but Separated | 3.0% | 1.3% | 1.8% |
| Single Population | 58.8% | 36.4% | 50.2% |
| Never Married | 38.4% | 23.4% | 33.8% |
| Divorced | 14.5% | 3.7% | 10.8% |
| Widowed | 5.9% | 9.4% | 5.6% |
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| Household Size | 2.32 | 2.84 | 2.60 |
| Households | 682 | 424 | 124,010,992 |
| Family Households | 410 | 317 | 80,755,759 |
| Married couple, w/children | 22.2% | 45.1% | 30.5% |
| Married couple, no children | 31.2% | 36.9% | 42.9% |
| Non Family Households | 272 | 107 | 43,255,233 |
| Single householder, w/children | 29.8% | 12.3% | 15.8% |
| Single householder, no children | 16.8% | 5.7% | 10.8% |