84 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Wellington | 1 | 7,530 | 7,705 | -0.41% | 988 | 8 | City |
| Wellington | 2 | 7,530 | 7,682 | -0.41% | 988 | 8 | City |
| Belle Plaine | 3 | 3,037 | 3,055 | -0.3% | 75 | 40 | Township |
| Belle Plaine | 4 | 3,037 | 3,051 | -0.3% | 75 | 40 | Township |
| Oxford | 5 | 2,062 | 2,029 | 0.68% | 745 | 3 | Township |
| Oxford | 6 | 2,062 | 2,030 | 0.68% | 745 | 3 | Township |
| Gore | 7 | 1,960 | 1,863 | 0.05% | 61 | 32 | Township |
| Gore | 8 | 1,960 | 1,862 | 0.05% | 61 | 32 | Township |
| Belle Plaine | 9 | 1,438 | 1,472 | -0.48% | 1,733 | 1 | City |
| Belle Plaine | 10 | 1,438 | 1,470 | -0.48% | 1,733 | 1 | City |
| Oxford | 11 | 1,237 | 1,249 | -0.56% | 32 | 38 | Township |
| Oxford | 12 | 1,237 | 1,247 | -0.56% | 32 | 38 | Township |
| Conway | 13 | 1,148 | 1,108 | 0.7% | 32 | 36 | Township |
| Conway | 14 | 1,148 | 1,107 | 0.7% | 32 | 36 | Township |
| Conway Springs | 15 | 1,145 | 1,094 | 0.88% | 1,160 | 1 | City |
| Conway Springs | 16 | 1,145 | 1,095 | 0.88% | 1,160 | 1 | City |
| Oxford | 17 | 1,034 | 1,042 | -0.19% | 1,141 | 1 | City |
| Oxford | 18 | 1,034 | 1,041 | -0.19% | 1,141 | 1 | City |
| Milton | 19 | 1,023 | 1,048 | -1.45% | 28 | 36 | Township |
| Milton | 20 | 1,023 | 1,048 | -1.45% | 28 | 36 | Township |
| Caldwell | 21 | 994 | 1,026 | -0.6% | 920 | 1 | City |
| Caldwell | 22 | 994 | 1,023 | -0.6% | 920 | 1 | City |
| London | 23 | 711 | 706 | 0% | 17 | 41 | Township |
| London | 24 | 711 | 706 | 0% | 17 | 41 | Township |
| Springdale | 25 | 685 | 668 | 0.44% | 19 | 36 | Township |
| Springdale | 26 | 685 | 668 | 0.44% | 19 | 36 | Township |
| Dixon | 27 | 592 | 605 | -0.5% | 16 | 36 | Township |
| Dixon | 28 | 592 | 604 | -0.5% | 16 | 36 | Township |
| South Haven | 29 | 532 | 533 | -0.19% | 10 | 54 | Township |
| South Haven | 30 | 532 | 531 | -0.19% | 10 | 54 | Township |
| Argonia | 31 | 444 | 457 | -0.67% | 636 | 1 | City |
| Argonia | 32 | 444 | 456 | -0.67% | 636 | 1 | City |
| Eden | 33 | 408 | 408 | 0% | 11 | 37 | Township |
| Eden | 34 | 408 | 407 | 0% | 11 | 37 | Township |
| South Haven | 35 | 325 | 326 | 0% | 325 | 1 | City |
| South Haven | 36 | 325 | 325 | 0% | 325 | 1 | City |
| Wellington | 37 | 320 | 321 | -0.31% | 10 | 31 | Township |
| Wellington | 38 | 320 | 320 | -0.31% | 10 | 31 | Township |
| Milton | 39 | 307 | 310 | -0.65% | 10 | 30 | Township |
| Milton | 40 | 307 | 311 | -0.65% | 10 | 30 | Township |
| Avon | 41 | 291 | 290 | 0.34% | 8 | 36 | Township |
| Avon | 42 | 291 | 289 | 0.34% | 8 | 36 | Township |
| Harmon | 43 | 256 | 255 | 0.39% | 8 | 31 | Township |
| Harmon | 44 | 256 | 254 | 0.39% | 8 | 31 | Township |
| Seventy-Six | 45 | 233 | 231 | -0.43% | 7 | 35 | Township |
| Seventy-Six | 46 | 233 | 230 | -0.43% | 7 | 35 | Township |
| Creek | 47 | 199 | 201 | -0.5% | 5 | 37 | Township |
| Creek | 48 | 199 | 200 | -0.5% | 5 | 37 | Township |
| Palestine | 49 | 185 | 187 | -0.54% | 7 | 28 | Township |
| Palestine | 50 | 185 | 186 | -0.54% | 7 | 28 | Township |
| Illinois | 51 | 171 | 171 | 0% | 5 | 36 | Township |
| Illinois | 52 | 171 | 170 | 0% | 5 | 36 | Township |
| Geuda Springs | 53 | 154 | 154 | 0% | 448 | 0 | City |
| Geuda Springs | 54 | 154 | 154 | 0% | 448 | 0 | City |
| Caldwell | 55 | 143 | 143 | 0% | 3 | 53 | Township |
| Caldwell | 56 | 143 | 143 | 0% | 3 | 53 | Township |
| Guelph | 57 | 143 | 144 | -0.69% | 3 | 55 | Township |
| Guelph | 58 | 143 | 144 | -0.69% | 3 | 55 | Township |
| Milton | 59 | 142 | 299 | -0.7% | 32 | 4 | CDP |
| Ryan | 60 | 141 | 141 | 0% | 4 | 36 | Township |
| Ryan | 61 | 141 | 141 | 0% | 4 | 36 | Township |
| Falls | 62 | 135 | 133 | 0.75% | 3 | 54 | Township |
| Falls | 63 | 135 | 133 | 0.75% | 3 | 54 | Township |
| Sumner | 64 | 130 | 123 | 1.56% | 4 | 36 | Township |
| Sumner | 65 | 130 | 123 | 1.56% | 4 | 36 | Township |
| Jackson | 66 | 123 | 124 | -0.81% | 3 | 36 | Township |
| Jackson | 67 | 123 | 124 | -0.81% | 3 | 36 | Township |
| Valverde | 68 | 103 | 104 | -0.96% | 3 | 36 | Township |
| Valverde | 69 | 103 | 104 | -0.96% | 3 | 36 | Township |
| Peck | 70 | 102 | 118 | 6.25% | 288 | 0 | CDP |
| Mayfield | 71 | 73 | 73 | 0% | 247 | 0 | City |
| Mayfield | 72 | 73 | 73 | 0% | 247 | 0 | City |
| Greene | 73 | 72 | 72 | -1.37% | 2 | 36 | Township |
| Greene | 74 | 72 | 72 | -1.37% | 2 | 36 | Township |
| Bluff | 75 | 62 | 59 | 3.33% | 1 | 53 | Township |
| Bluff | 76 | 62 | 59 | 3.33% | 1 | 53 | Township |
| Chikaskia | 77 | 58 | 55 | 3.57% | 2 | 36 | Township |
| Chikaskia | 78 | 58 | 55 | 3.57% | 2 | 36 | Township |
| Milan | 79 | 52 | 52 | 0% | 394 | 0 | City |
| Milan | 80 | 52 | 52 | 0% | 394 | 0 | City |
| Hunnewell | 81 | 43 | 42 | 0% | 77 | 1 | City |
| Hunnewell | 82 | 43 | 42 | 0% | 77 | 1 | City |
| Morris | 83 | 19 | 19 | 0% | 1 | 36 | Township |
| Morris | 84 | 19 | 19 | 0% | 1 | 36 | Township |
Wellington is the largest city in Sumner County, with a population of 7,530.
Morris is the smallest city in Sumner County, with a population of 19.
There are 84 cities in Sumner County, Kansas.