See County Population Estimates map.
| County | July 1, 2004 Estimate | 2000 Census | 2000-04 Difference | Difference Rank | 2000-04 % Change | % Change Rank |
|---|---|---|---|---|---|---|
| Adair | 24,666 | 24,977 | -311 | 105 | -1.25% | 89 |
| Andrew | 16,834 | 16,492 | 342 | 50 | 2.07% | 49 |
| Atchison | 6,302 | 6,430 | -128 | 89 | -1.99% | 98 |
| Audrain | 25,658 | 25,853 | -195 | 96 | -0.75% | 83 |
| Barry | 35,314 | 34,010 | 1,304 | 30 | 3.83% | 32 |
| Barton | 13,070 | 12,541 | 529 | 44 | 4.22% | 30 |
| Bates | 16,965 | 16,653 | 312 | 52 | 1.87% | 53 |
| Benton | 18,519 | 17,180 | 1,339 | 27 | 7.79% | 11 |
| Bollinger | 12,341 | 12,029 | 312 | 53 | 2.59% | 44 |
| Boone | 141,367 | 135,454 | 5,913 | 9 | 4.37% | 26 |
| Buchanan | 84,825 | 85,998 | -1,173 | 113 | -1.36% | 93 |
| Butler | 40,989 | 40,867 | 122 | 69 | 0.30% | 74 |
| Caldwell | 9,204 | 8,969 | 235 | 57 | 2.62% | 42 |
| Callaway | 42,086 | 40,766 | 1,320 | 29 | 3.24% | 37 |
| Camden | 38,702 | 37,051 | 1,651 | 24 | 4.46% | 25 |
| Cape Girardeau | 70,730 | 68,693 | 2,037 | 21 | 2.97% | 41 |
| Carroll | 10,129 | 10,285 | -156 | 93 | -1.52% | 95 |
| Carter | 5,963 | 5,941 | 22 | 76 | 0.37% | 73 |
| Cass | 91,593 | 82,092 | 9,501 | 5 | 11.57% | 5 |
| Cedar | 13,894 | 13,733 | 161 | 63 | 1.17% | 61 |
| Chariton | 8,142 | 8,438 | -296 | 104 | -3.51% | 108 |
| Christian | 64,273 | 54,285 | 9,988 | 4 | 18.40% | 1 |
| Clark | 7,356 | 7,416 | -60 | 80 | -0.81% | 84 |
| Clay | 197,588 | 184,006 | 13,582 | 2 | 7.38% | 13 |
| Clinton | 20,683 | 18,979 | 1,704 | 23 | 8.98% | 9 |
| Cole | 71,996 | 71,397 | 599 | 41 | 0.84% | 67 |
| Cooper | 17,259 | 16,670 | 589 | 42 | 3.53% | 34 |
| Crawford | 23,647 | 22,804 | 843 | 35 | 3.70% | 33 |
| Dade | 7,829 | 7,923 | -94 | 86 | -1.19% | 88 |
| Dallas | 16,328 | 15,661 | 667 | 39 | 4.26% | 29 |
| Daviess | 8,166 | 8,016 | 150 | 66 | 1.87% | 54 |
| DeKalb | 12,488 | 11,597 | 891 | 34 | 7.68% | 12 |
| Dent | 15,067 | 14,927 | 140 | 68 | 0.94% | 63 |
| Douglas | 13,546 | 13,084 | 462 | 46 | 3.53% | 35 |
| Dunklin | 32,488 | 33,155 | -667 | 110 | -2.01% | 99 |
| Franklin | 98,234 | 93,807 | 4,427 | 13 | 4.72% | 22 |
| Gasconade | 15,612 | 15,342 | 270 | 54 | 1.76% | 56 |
| Gentry | 6,523 | 6,861 | -338 | 106 | -4.93% | 114 |
| Greene | 247,932 | 240,391 | 7,541 | 6 | 3.14% | 40 |
| Grundy | 10,183 | 10,432 | -249 | 99 | -2.39% | 102 |
| Harrison | 8,816 | 8,850 | -34 | 78 | -0.38% | 79 |
| Henry | 22,701 | 21,997 | 704 | 37 | 3.20% | 38 |
| Hickory | 9,167 | 8,940 | 227 | 58 | 2.54% | 45 |
| Holt | 5,087 | 5,351 | -264 | 100 | -4.93% | 115 |
| Howard | 9,940 | 10,212 | -272 | 101 | -2.66% | 103 |
| Howell | 37,995 | 37,238 | 757 | 36 | 2.03% | 50 |
| Iron | 10,329 | 10,697 | -368 | 107 | -3.44% | 107 |
| Jackson | 660,095 | 654,880 | 5,215 | 10 | 0.80% | 68 |
| Jasper | 109,460 | 104,686 | 4,774 | 12 | 4.56% | 23 |
| Jefferson | 210,397 | 198,099 | 12,298 | 3 | 6.21% | 16 |
| Johnson | 50,669 | 48,258 | 2,411 | 17 | 5.00% | 18 |
| Knox | 4,199 | 4,361 | -162 | 95 | -3.71% | 111 |
| Laclede | 33,617 | 32,513 | 1,104 | 31 | 3.40% | 36 |
| Lafayette | 33,134 | 32,960 | 174 | 62 | 0.53% | 71 |
| Lawrence | 36,710 | 35,204 | 1,506 | 25 | 4.28% | 27 |
| Lewis | 10,261 | 10,494 | -233 | 98 | -2.22% | 100 |
| Lincoln | 45,816 | 38,944 | 6,872 | 8 | 17.65% | 2 |
| Linn | 13,281 | 13,754 | -473 | 108 | -3.44% | 106 |
| Livingston | 14,269 | 14,558 | -289 | 103 | -1.99% | 97 |
| Macon | 15,554 | 15,762 | -208 | 97 | -1.32% | 91 |
| Madison | 11,948 | 11,800 | 148 | 67 | 1.25% | 59 |
| Maries | 8,877 | 8,903 | -26 | 77 | -0.29% | 77 |
| Marion | 28,410 | 28,289 | 121 | 70 | 0.43% | 72 |
| McDonald | 22,363 | 21,681 | 682 | 38 | 3.15% | 39 |
| Mercer | 3,618 | 3,757 | -139 | 90 | -3.70% | 110 |
| Miller | 24,624 | 23,564 | 1,060 | 32 | 4.50% | 24 |
| Mississippi | 13,697 | 13,427 | 270 | 55 | 2.01% | 51 |
| Moniteau | 15,042 | 14,827 | 215 | 60 | 1.45% | 58 |
| Monroe | 9,467 | 9,311 | 156 | 65 | 1.68% | 57 |
| Montgomery | 12,085 | 12,136 | -51 | 79 | -0.42% | 80 |
| Morgan | 20,263 | 19,309 | 954 | 33 | 4.94% | 19 |
| New Madrid | 18,969 | 19,760 | -791 | 112 | -4.00% | 113 |
| Newton | 54,775 | 52,636 | 2,139 | 19 | 4.06% | 31 |
| Nodaway | 21,754 | 21,912 | -158 | 94 | -0.72% | 82 |
| Oregon | 10,441 | 10,344 | 97 | 71 | 0.94% | 64 |
| Osage | 13,324 | 13,062 | 262 | 56 | 2.01% | 52 |
| Ozark | 9,431 | 9,542 | -111 | 87 | -1.16% | 87 |
| Pemiscot | 19,571 | 20,047 | -476 | 109 | -2.37% | 101 |
| Perry | 18,289 | 18,132 | 157 | 64 | 0.87% | 66 |
| Pettis | 39,753 | 39,403 | 350 | 49 | 0.89% | 65 |
| Phelps | 41,726 | 39,825 | 1,901 | 22 | 4.77% | 21 |
| Pike | 18,403 | 18,351 | 52 | 75 | 0.28% | 75 |
| Platte | 80,967 | 73,781 | 7,186 | 7 | 9.74% | 7 |
| Polk | 28,320 | 26,992 | 1,328 | 28 | 4.92% | 20 |
| Pulaski | 44,478 | 41,165 | 3,313 | 14 | 8.05% | 10 |
| Putnam | 5,074 | 5,223 | -149 | 92 | -2.85% | 104 |
| Ralls | 9,682 | 9,626 | 56 | 74 | 0.58% | 70 |
| Randolph | 25,120 | 24,663 | 457 | 47 | 1.85% | 55 |
| Ray | 23,937 | 23,354 | 583 | 43 | 2.50% | 46 |
| Reynolds | 6,603 | 6,689 | -86 | 83 | -1.29% | 90 |
| Ripley | 13,839 | 13,509 | 330 | 51 | 2.44% | 47 |
| Saline | 23,059 | 23,756 | -697 | 111 | -2.93% | 105 |
| Schuyler | 4,348 | 4,170 | 178 | 61 | 4.27% | 28 |
| Scotland | 4,907 | 4,983 | -76 | 82 | -1.53% | 96 |
| Scott | 40,891 | 40,422 | 469 | 45 | 1.16% | 62 |
| Shannon | 8,381 | 8,324 | 57 | 73 | 0.68% | 69 |
| Shelby | 6,709 | 6,799 | -90 | 85 | -1.32% | 92 |
| St. Charles | 320,734 | 283,883 | 36,851 | 1 | 12.98% | 4 |
| St. Clair | 9,540 | 9,652 | -112 | 88 | -1.16% | 86 |
| St. Francois | 60,724 | 55,641 | 5,083 | 11 | 9.14% | 8 |
| St. Louis City | 343,279 | 348,189 | -4,910 | 114 | -1.41% | 94 |
| St. Louis | 1,009,235 | 1,016,315 | -7,080 | 115 | -0.70% | 81 |
| Ste. Genevieve | 18,264 | 17,842 | 422 | 48 | 2.37% | 48 |
| Stoddard | 29,773 | 29,705 | 68 | 72 | 0.23% | 76 |
| Stone | 30,720 | 28,658 | 2,062 | 20 | 7.20% | 14 |
| Sullivan | 6,938 | 7,219 | -281 | 102 | -3.89% | 112 |
| Taney | 41,939 | 39,703 | 2,236 | 18 | 5.63% | 17 |
| Texas | 24,476 | 23,003 | 1,473 | 26 | 6.40% | 15 |
| Vernon | 20,383 | 20,454 | -71 | 81 | -0.35% | 78 |
| Warren | 27,809 | 24,525 | 3,284 | 15 | 13.39% | 3 |
| Washington | 23,955 | 23,344 | 611 | 40 | 2.62% | 43 |
| Wayne | 13,112 | 13,259 | -147 | 91 | -1.11% | 85 |
| Webster | 34,133 | 31,045 | 3,088 | 16 | 9.95% | 6 |
| Worth | 2,294 | 2,382 | -88 | 84 | -3.69% | 109 |
| Wright | 18,177 | 17,955 | 222 | 59 | 1.24% | 60 |
