| | Gardiner, ME | Rockland, ME | United States |
| Population | 5,944 | 6,977 | 329,725,481 |
| Female Population | 51.0% | 53.1% | 50.5% |
| Male Population | 49.0% | 46.9% | 49.5% |
| Median Age | 42 | 45.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 5,782 | 7,295 | 309,327,143 |
| Population - 2000 | 6,198 | 7,609 | 285,036,114 |
| Population - 1990 | 6,746 | 7,972 | 251,960,433 |
| Pop. 2000 to Now | -8.3% | -5.6% | 15.6% |
| Pop. 1990 to Now | -15.7% | -9.9% | 30.8% |
| space4 | | | |
| Population Density | 379.2 | 543.3 | 93.4 |
| Land Area | 15.7 | 12.8 | 3,531,905.4 |
| Water Area | 0.9 | 2.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Gardiner, ME | Rockland, ME | United States |
| Age 0 to 4 | 5.0% | 3.8% | 5.9% |
| Age 5 to 9 | 6.7% | 5.3% | 6.1% |
| Age 10 to 14 | 3.6% | 6.4% | 6.6% |
| Age 15 to 17 | 4.1% | 3.5% | 3.9% |
| Age 18 to 20 | 2.0% | 2.7% | 4.0% |
| Age 21 to 24 | 10.2% | 4.4% | 5.2% |
| Age 25 to 34 | 10.9% | 13.6% | 13.8% |
| Age 35 to 44 | 9.7% | 9.7% | 12.9% |
| Age 45 to 54 | 16.6% | 8.3% | 12.6% |
| Age 55 to 59 | 5.8% | 9.1% | 6.7% |
| Age 60 to 64 | 6.2% | 11.2% | 6.3% |
| Age 65 to 74 | 11.0% | 12.2% | 9.6% |
| Age 75 to 84 | 5.9% | 7.1% | 4.5% |
| Age 85 and over | 2.2% | 2.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Gardiner, ME | Rockland, ME | United States |
| White | 95.8% | 95.4% | 59.4% |
| Black | 0.3% | 0.0% | 12.2% |
| Asian | 0.1% | 0.9% | 5.6% |
| Native American | 0.3% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.5% | 0.0% | 0.4% |
| Two or More Races | 1.3% | 2.6% | 3.2% |
| Hispanic | 1.8% | 0.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Gardiner, ME | Rockland, ME | United States |
| Married Population | 50.4% | 38.6% | 49.8% |
| Currently Married | 50.0% | 37.2% | 48.0% |
| Married but Separated | 0.4% | 1.5% | 1.8% |
| Single Population | 49.6% | 61.4% | 50.2% |
| Never Married | 30.8% | 33.6% | 33.8% |
| Divorced | 13.3% | 20.6% | 10.8% |
| Widowed | 5.6% | 7.2% | 5.6% |
| space5 | | | |
| Household Size | 2.39 | 2.01 | 2.60 |
| Households | 2,441 | 3,367 | 124,010,992 |
| Family Households | 1,502 | 1,437 | 80,755,759 |
| Married couple, w/children | 20.6% | 21.5% | 30.5% |
| Married couple, no children | 53.8% | 53.0% | 42.9% |
| Non Family Households | 939 | 1,930 | 43,255,233 |
| Single householder, w/children | 13.4% | 21.2% | 15.8% |
| Single householder, no children | 12.3% | 4.4% | 10.8% |