8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Slidell | 1 | 28,345 | 28,629 | -0.17% | 1,856 | 15 | City |
| Mandeville | 2 | 13,046 | 12,826 | 0.28% | 1,394 | 9 | City |
| Covington | 3 | 11,744 | 11,569 | 0.25% | 1,464 | 8 | City |
| Abita Springs | 4 | 2,814 | 2,628 | 1.11% | 610 | 5 | Town |
| Pearl River | 5 | 2,700 | 2,540 | 1.01% | 723 | 4 | Town |
| Madisonville | 6 | 889 | 847 | 0.79% | 352 | 3 | Town |
| Folsom | 7 | 856 | 775 | 1.66% | 430 | 2 | Village |
| Sun | 8 | 401 | 394 | 0.25% | 94 | 4 | Village |
Slidell is the largest city in St. Tammany Parish, with a population of 28,345.
Sun is the smallest city in St. Tammany Parish, with a population of 401.
There are 8 cities in St. Tammany Parish, Louisiana.