| | Diamondhead, MS | Mandeville, LA | United States |
| Population | 9,417 | 12,985 | 329,725,481 |
| Female Population | 50.1% | 51.4% | 50.5% |
| Male Population | 49.9% | 48.7% | 49.5% |
| Median Age | 50.5 | 45.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,375 | 12,137 | 309,327,143 |
| Population - 2000 | 5,912 | 10,489 | 285,036,114 |
| Population - 1990 | 2,661 | 7,083 | 251,960,433 |
| Pop. 2000 to Now | 36.3% | 19.7% | 15.6% |
| Pop. 1990 to Now | 202.8% | 77.3% | 30.8% |
| space4 | | | |
| Population Density | 931.6 | 1,870.0 | 93.4 |
| Land Area | 10.1 | 6.9 | 3,531,905.4 |
| Water Area | 2.5 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Diamondhead, MS | Mandeville, LA | United States |
| Age 0 to 4 | 9.2% | 3.1% | 5.9% |
| Age 5 to 9 | 2.2% | 6.0% | 6.1% |
| Age 10 to 14 | 5.1% | 9.9% | 6.6% |
| Age 15 to 17 | 1.8% | 5.1% | 3.9% |
| Age 18 to 20 | 0.5% | 3.5% | 4.0% |
| Age 21 to 24 | 6.0% | 2.0% | 5.2% |
| Age 25 to 34 | 11.2% | 9.3% | 13.8% |
| Age 35 to 44 | 8.3% | 10.6% | 12.9% |
| Age 45 to 54 | 9.9% | 15.4% | 12.6% |
| Age 55 to 59 | 8.5% | 11.1% | 6.7% |
| Age 60 to 64 | 12.7% | 4.4% | 6.3% |
| Age 65 to 74 | 12.1% | 11.3% | 9.6% |
| Age 75 to 84 | 8.1% | 6.5% | 4.5% |
| Age 85 and over | 4.3% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Diamondhead, MS | Mandeville, LA | United States |
| White | 88.4% | 92.5% | 59.4% |
| Black | 1.3% | 0.8% | 12.2% |
| Asian | 0.0% | 2.3% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 4.0% | 1.0% | 3.2% |
| Hispanic | 6.0% | 3.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Diamondhead, MS | Mandeville, LA | United States |
| Married Population | 58.3% | 57.2% | 49.8% |
| Currently Married | 57.1% | 55.9% | 48.0% |
| Married but Separated | 1.2% | 1.3% | 1.8% |
| Single Population | 41.7% | 42.8% | 50.2% |
| Never Married | 15.6% | 23.7% | 33.8% |
| Divorced | 18.2% | 14.4% | 10.8% |
| Widowed | 7.9% | 4.7% | 5.6% |
| space5 | | | |
| Household Size | 2.26 | 2.43 | 2.60 |
| Households | 4,160 | 5,272 | 124,010,992 |
| Family Households | 2,881 | 3,495 | 80,755,759 |
| Married couple, w/children | 21.4% | 30.8% | 30.5% |
| Married couple, no children | 52.5% | 48.5% | 42.9% |
| Non Family Households | 1,279 | 1,777 | 43,255,233 |
| Single householder, w/children | 17.1% | 16.7% | 15.8% |
| Single householder, no children | 9.0% | 4.0% | 10.8% |