(Links below lead to Quick Facts for Ohio Counties: People, Business & Geography at U.S. Census Bureau.)
| Area | 7/1/2008 | 7/1/2007 | 7/1/2006 | 7/1/2005 | 7/1/2004 | 7/1/2003 | 7/1/2002 | 7/1/2001 | 7/1/2000 | Census 2000 |
| Ohio | 11,485,910 | 11,477,641 | 11,458,390 | 11,450,954 | 11,445,095 | 11,430,306 | 11,410,582 | 11,391,298 | 11,363,719 | 11,353,140 |
|---|---|---|---|---|---|---|---|---|---|---|
| Adams County | 28,213 | 28,103 | 28,195 | 28,191 | 28,072 | 27,920 | 27,709 | 27,482 | 27,338 | 27,330 |
| Allen County | 105,168 | 105,133 | 105,202 | 105,550 | 105,793 | 106,534 | 107,847 | 108,196 | 108,577 | 108,473 |
| Ashland County | 55,125 | 54,843 | 54,327 | 53,978 | 53,624 | 53,464 | 53,051 | 52,827 | 52,584 | 52,523 |
| Ashtabula County | 100,648 | 101,151 | 101,471 | 102,005 | 102,235 | 102,453 | 102,597 | 102,663 | 102,746 | 102,728 |
| Athens County | 63,255 | 63,200 | 63,193 | 63,175 | 62,499 | 63,270 | 63,052 | 62,832 | 62,319 | 62,223 |
| Auglaize County | 46,576 | 46,376 | 46,392 | 46,620 | 46,384 | 46,304 | 46,389 | 46,568 | 46,593 | 46,611 |
| Belmont County | 67,975 | 68,292 | 68,567 | 68,675 | 69,002 | 69,261 | 69,657 | 69,566 | 70,113 | 70,226 |
| Brown County | 43,960 | 43,851 | 43,715 | 43,681 | 43,623 | 43,511 | 43,208 | 42,772 | 42,583 | 42,285 |
| Butler County | 360,765 | 357,908 | 353,486 | 348,243 | 344,784 | 341,667 | 338,891 | 336,553 | 333,683 | 332,807 |
| Carroll County | 28,439 | 28,545 | 28,781 | 28,883 | 29,115 | 29,185 | 29,098 | 28,933 | 28,866 | 28,836 |
| Champaign County | 39,650 | 39,465 | 39,435 | 39,193 | 39,237 | 39,151 | 39,132 | 38,966 | 38,925 | 38,890 |
| Clark County | 139,859 | 140,293 | 140,966 | 141,554 | 141,568 | 141,909 | 143,402 | 143,926 | 144,660 | 144,742 |
| Clermont County | 195,385 | 193,729 | 191,703 | 189,313 | 187,297 | 184,590 | 182,550 | 180,392 | 178,630 | 177,977 |
| Clinton County | 43,200 | 42,962 | 42,828 | 42,074 | 41,804 | 41,445 | 41,221 | 40,913 | 40,662 | 40,543 |
| Columbiana County | 107,873 | 108,587 | 109,191 | 109,529 | 110,429 | 110,844 | 111,069 | 111,398 | 112,092 | 112,075 |
| Coshocton County | 35,981 | 36,257 | 36,495 | 36,653 | 36,846 | 36,842 | 36,856 | 36,814 | 36,690 | 36,655 |
| Crawford County | 43,696 | 44,104 | 44,470 | 45,164 | 45,491 | 45,720 | 46,170 | 46,509 | 46,881 | 46,966 |
| Cuyahoga County | 1,283,925 | 1,295,187 | 1,307,936 | 1,325,424 | 1,342,569 | 1,356,396 | 1,369,638 | 1,381,701 | 1,392,111 | 1,393,978 |
| Darke County | 52,027 | 52,176 | 52,301 | 52,639 | 52,808 | 52,873 | 52,832 | 53,029 | 53,292 | 53,309 |
| Defiance County | 38,637 | 38,613 | 38,717 | 38,597 | 38,754 | 38,924 | 39,129 | 39,371 | 39,452 | 39,500 |
| Delaware County | 165,026 | 160,358 | 155,315 | 149,334 | 141,936 | 134,874 | 126,988 | 119,083 | 111,710 | 109,989 |
| Erie County | 77,062 | 77,162 | 77,423 | 77,786 | 78,365 | 78,472 | 78,643 | 79,228 | 79,605 | 79,551 |
| Fairfield County | 142,223 | 141,045 | 139,387 | 137,511 | 135,094 | 132,006 | 128,872 | 125,971 | 123,420 | 122,759 |
| Fayette County | 28,319 | 28,296 | 28,213 | 28,217 | 28,082 | 28,135 | 28,153 | 28,170 | 28,435 | 28,433 |
| Franklin County | 1,129,067 | 1,116,949 | 1,107,090 | 1,098,818 | 1,094,588 | 1,091,389 | 1,086,682 | 1,082,170 | 1,072,287 | 1,068,978 |
| Fulton County | 42,485 | 42,482 | 42,512 | 42,633 | 42,576 | 42,254 | 42,205 | 42,152 | 42,134 | 42,084 |
| Gallia County | 30,912 | 30,816 | 30,843 | 30,922 | 30,967 | 31,040 | 31,077 | 31,036 | 31,094 | 31,069 |
| Geauga County | 94,753 | 94,696 | 94,577 | 94,323 | 93,791 | 93,454 | 92,284 | 91,605 | 91,209 | 90,895 |
| Greene County | 159,190 | 158,594 | 157,561 | 156,129 | 155,412 | 153,182 | 151,447 | 149,529 | 148,207 | 147,886 |
| Guernsey County | 40,177 | 40,375 | 40,409 | 40,614 | 40,859 | 41,050 | 40,952 | 40,833 | 40,791 | 40,792 |
| Hamilton County | 851,494 | 853,928 | 847,184 | 846,725 | 846,254 | 847,161 | 848,120 | 849,297 | 844,290 | 845,303 |
| Hancock County | 74,273 | 74,265 | 73,717 | 73,260 | 73,278 | 72,914 | 72,511 | 71,929 | 71,327 | 71,295 |
| Hardin County | 31,948 | 31,864 | 31,683 | 31,710 | 31,901 | 31,548 | 31,697 | 31,693 | 31,932 | 31,945 |
| Harrison County | 15,387 | 15,482 | 15,481 | 15,589 | 15,602 | 15,805 | 15,777 | 15,733 | 15,853 | 15,856 |
| Henry County | 28,841 | 28,902 | 29,210 | 29,185 | 29,160 | 29,143 | 29,236 | 29,135 | 29,209 | 29,210 |
| Highland County | 42,349 | 42,586 | 42,506 | 42,124 | 42,266 | 41,765 | 41,540 | 41,143 | 41,019 | 40,875 |
| Hocking County | 28,975 | 28,920 | 28,657 | 28,733 | 28,698 | 28,617 | 28,518 | 28,370 | 28,241 | 28,241 |
| Holmes County | 41,445 | 41,268 | 41,341 | 41,237 | 41,060 | 40,602 | 40,328 | 39,736 | 39,049 | 38,943 |
| Huron County | 59,659 | 59,715 | 59,787 | 59,897 | 59,834 | 59,792 | 59,825 | 59,562 | 59,577 | 59,487 |
| Jackson County | 33,270 | 33,211 | 33,170 | 33,284 | 33,069 | 32,912 | 32,883 | 32,695 | 32,636 | 32,641 |
| Jefferson County | 68,526 | 68,756 | 69,348 | 70,091 | 70,844 | 71,396 | 71,957 | 72,798 | 73,637 | 73,894 |
| Knox County | 59,324 | 58,890 | 58,368 | 58,009 | 57,487 | 56,835 | 56,133 | 55,370 | 54,643 | 54,500 |
| Lake County | 234,030 | 233,013 | 232,318 | 232,008 | 232,004 | 231,094 | 230,541 | 229,256 | 227,656 | 227,511 |
| Lawrence County | 62,573 | 62,598 | 62,645 | 62,443 | 62,153 | 62,177 | 61,866 | 61,988 | 62,252 | 62,319 |
| Licking County | 157,721 | 156,734 | 155,315 | 153,974 | 152,125 | 150,194 | 148,439 | 147,326 | 146,071 | 145,491 |
| Logan County | 46,220 | 46,282 | 46,069 | 46,286 | 46,435 | 46,400 | 46,214 | 45,947 | 46,016 | 46,005 |
| Lorain County | 304,373 | 302,687 | 301,215 | 298,889 | 295,327 | 292,991 | 289,198 | 286,803 | 285,132 | 284,664 |
| Lucas County | 440,456 | 442,408 | 443,908 | 446,458 | 449,044 | 452,015 | 453,244 | 454,392 | 454,872 | 455,054 |
| Madison County | 41,861 | 41,673 | 41,259 | 40,809 | 40,736 | 40,592 | 40,361 | 40,178 | 40,212 | 40,213 |
| Mahoning County | 237,978 | 240,197 | 243,487 | 245,669 | 248,176 | 250,399 | 252,204 | 254,850 | 257,042 | 257,555 |
| Marion County | 65,768 | 65,536 | 65,520 | 65,716 | 65,740 | 65,903 | 65,880 | 66,005 | 66,150 | 66,217 |
| Medina County | 171,210 | 169,302 | 167,804 | 165,660 | 163,642 | 160,754 | 157,889 | 154,615 | 151,836 | 151,095 |
| Meigs County | 22,722 | 22,830 | 22,895 | 23,072 | 23,096 | 23,131 | 23,108 | 23,021 | 23,026 | 23,072 |
| Mercer County | 40,818 | 40,799 | 40,764 | 40,761 | 40,732 | 40,715 | 40,775 | 40,787 | 40,909 | 40,924 |
| Miami County | 101,085 | 100,846 | 100,858 | 100,595 | 100,010 | 99,519 | 99,202 | 99,096 | 98,972 | 98,868 |
| Monroe County | 14,221 | 14,250 | 14,359 | 14,551 | 14,794 | 14,806 | 14,849 | 15,027 | 15,167 | 15,180 |
| Montgomery County | 534,626 | 537,756 | 540,718 | 544,475 | 547,760 | 550,411 | 552,310 | 555,097 | 558,516 | 559,062 |
| Morgan County | 14,510 | 14,602 | 14,637 | 14,718 | 14,720 | 14,673 | 14,681 | 14,792 | 14,876 | 14,897 |
| Morrow County | 34,455 | 34,477 | 34,189 | 34,027 | 33,832 | 33,373 | 32,867 | 32,390 | 31,794 | 31,628 |
| Muskingum County | 85,087 | 85,230 | 85,378 | 85,138 | 85,155 | 85,092 | 85,074 | 84,695 | 84,708 | 84,585 |
| Noble County | 14,333 | 14,356 | 14,380 | 13,990 | 14,170 | 14,088 | 13,958 | 13,935 | 14,101 | 14,058 |
| Ottawa County | 40,823 | 41,069 | 41,200 | 41,294 | 41,302 | 41,127 | 40,915 | 40,972 | 41,004 | 40,985 |
| Paulding County | 19,096 | 19,172 | 19,260 | 19,409 | 19,480 | 19,637 | 19,808 | 20,091 | 20,234 | 20,293 |
| Perry County | 35,241 | 34,833 | 34,809 | 34,791 | 34,752 | 34,666 | 34,459 | 34,296 | 34,113 | 34,078 |
| Pickaway County | 54,544 | 54,163 | 53,308 | 52,384 | 51,774 | 51,644 | 51,557 | 52,264 | 52,816 | 52,727 |
| Pike County | 27,967 | 27,895 | 27,938 | 27,782 | 28,025 | 27,963 | 27,903 | 27,752 | 27,739 | 27,695 |
| Portage County | 155,991 | 155,348 | 154,581 | 155,056 | 154,837 | 154,473 | 153,692 | 153,026 | 152,383 | 152,061 |
| Preble County | 41,643 | 41,632 | 41,845 | 41,880 | 42,052 | 42,208 | 42,311 | 42,283 | 42,361 | 42,337 |
| Putnam County | 34,543 | 34,614 | 34,632 | 34,648 | 34,577 | 34,681 | 34,615 | 34,741 | 34,763 | 34,726 |
| Richland County | 124,999 | 125,868 | 126,298 | 126,935 | 127,451 | 127,817 | 128,059 | 128,006 | 128,799 | 128,852 |
| Ross County | 76,073 | 75,799 | 75,240 | 74,808 | 74,328 | 74,305 | 73,895 | 73,592 | 73,450 | 73,345 |
| Sandusky County | 60,637 | 60,927 | 61,110 | 61,233 | 61,431 | 61,398 | 61,684 | 61,675 | 61,808 | 61,792 |
| Scioto County | 76,587 | 76,449 | 76,177 | 76,194 | 76,378 | 77,170 | 77,919 | 78,391 | 79,098 | 79,195 |
| Seneca County | 56,461 | 56,688 | 56,860 | 57,246 | 57,532 | 57,755 | 57,943 | 58,314 | 58,607 | 58,683 |
| Shelby County | 48,919 | 48,748 | 48,551 | 48,462 | 48,262 | 48,265 | 48,235 | 48,263 | 47,990 | 47,910 |
| Stark County | 379,214 | 379,049 | 378,563 | 378,672 | 379,265 | 379,132 | 378,709 | 378,375 | 378,100 | 378,098 |
| Summit County | 542,562 | 543,734 | 544,674 | 545,347 | 545,545 | 545,637 | 545,771 | 545,179 | 543,578 | 542,899 |
| Trumbull County | 211,317 | 213,385 | 215,273 | 217,111 | 218,903 | 220,385 | 222,242 | 223,893 | 224,946 | 225,116 |
| Tuscarawas County | 91,348 | 91,263 | 91,085 | 91,309 | 91,576 | 91,419 | 91,374 | 91,138 | 91,029 | 90,914 |
| Union County | 48,223 | 47,611 | 46,615 | 45,391 | 44,644 | 43,719 | 42,901 | 42,479 | 41,195 | 40,909 |
| Van Wert County | 28,748 | 28,872 | 29,061 | 29,031 | 29,143 | 29,152 | 29,249 | 29,393 | 29,631 | 29,659 |
| Vinton County | 13,281 | 13,379 | 13,368 | 13,228 | 13,196 | 13,171 | 13,019 | 12,935 | 12,821 | 12,806 |
| Warren County | 207,353 | 203,606 | 198,817 | 194,076 | 187,593 | 180,709 | 173,733 | 166,811 | 160,687 | 158,383 |
| Washington County | 61,567 | 61,682 | 61,756 | 61,971 | 62,467 | 62,411 | 62,424 | 62,755 | 63,189 | 63,251 |
| Wayne County | 113,812 | 113,411 | 113,540 | 113,155 | 112,909 | 112,784 | 112,542 | 112,090 | 111,661 | 111,564 |
| Williams County | 38,158 | 38,303 | 38,306 | 38,387 | 38,596 | 38,654 | 38,914 | 39,067 | 39,205 | 39,188 |
| Wood County | 125,340 | 124,811 | 124,127 | 123,975 | 123,569 | 122,358 | 121,951 | 121,891 | 121,192 | 121,065 |
| Wyandot County | 22,354 | 22,419 | 22,525 | 22,668 | 22,800 | 22,730 | 22,772 | 22,777 | 22,910 | 22,908 |
Source: Population Division, U.S. Census Bureau