| Voter registration numbers and election results by county come from the Iowa Secretary of State's website.
Active voter registration numbers as of December 2012
IA-01
Democrat Bruce Braley lagged a little behind President Obama in fifteen counties but exceeded Obama's vote total in five counties: Black Hawk (where he has lived and worked for decades), Dubuque, Iowa, Jackson, and Poweshiek (where he grew up). Republican Ben Lange outperformed Mitt Romney in only two counties: Buchanan (where he lives and works) and Winneshiek.
| County |
Democrats |
Republicans |
no-party voters |
votes for Obama |
votes for Romney |
votes for Braley |
votes for Lange |
| Allamakee | 2,236 | 4,327 | 3,168 | 3,553 | 3,264 | 3,271 | 3,226 |
| Benton | 4,851 | 5,136 | 7,684 | 6,862 | 6,940 | 6,819 | 6,573 |
| Black Hawk | 29,503 | 20,892 | 31,879 | 39,806 | 26,219 | 40,749 | 24,078 |
| Bremer | 3,939 | 5,158 | 7493 | 6,763 | 6,405 | 6,707 | 6,170 |
| Buchanan | 3,982 | 3,231 | 6,579 | 5,911 | 4,450 | 5,413 | 4,885 |
| Clayton | 3,418 | 3,273 | 4,789 | 4,806 | 4,164 | 4,769 | 3,975 |
| Delaware | 2,612 | 3,854 | 4,889 | 4,616 | 4,636 | 4,418 | 4,632 |
| Dubuque | 25,376 | 14,989 | 22,711 | 28,768 | 21,280 | 29,129 | 19,569 |
| Fayette | 3,893 | 4,204 | 4,287 | 5,732 | 4,492 | 5,706 | 4,323 |
| Howard | 1,988 | 1,491 | 2,661 | 2,768 | 1,795 | 2,505 | 1,785 |
| Iowa | 2,885 | 3,795 | 4,918 | 4,144 | 4,569 | 4,182 | 4,284 |
| Jackson | 5,938 | 2,722 | 5,687 | 5,907 | 4,177 | 5,935 | 3,732 |
| Jones | 3,633 | 3,750 | 5,926 | 5,534 | 4,721 | 5,443 | 4,539 |
| Linn | 50,130 | 38,707 | 51,551 | 68,581 | 47,622 | 67,210 | 45,703 |
| Marshall | 7,919 | 7,951 | 9,533 | 10,257 | 8,472 | 9,480 | 8,168 |
| Mitchell | 1,859 | 2,569 | 2,783 | 2,831 | 2,643 | 2,531 | 2,540 |
| Poweshiek | 3,896 | 3,757 | 5,134 | 5,357 | 4,424 | 5,517 | 3,986 |
| Tama | 3,430 | 3,488 | 4,489 | 4,768 | 4,098 | 4,710 | 3,964 |
| Winnishiek | 3,679 | 4,550 | 5,300 | 6,256 | 4,622 | 5,819 | 4,646 |
| Worth | 1,604 | 1,823 | 2,100 | 2,350 | 1,744 | 2,109 | 1,687 |
| |
| total | 166,771 | 139,667 | 193,561 | 225,570 | 170,737 | 222,422 | 162,465 |
IA-02
Democrat Dave Loebsack lagged a little behind President Obama in sixteen counties but exceeded Obama's vote total in eight counties that he has represented for the past six years: Appanoose, Cedar, Davis, Lee, Monroe, Van Buren, Washington, and Wayne. Republican John Archer received more votes than Mitt Romney in only two counties, both new to Loebsack's district: Scott (where Archer lives and works) and Clinton.
| County |
Democrats |
Republicans |
no-party voters |
votes for Obama |
votes for Romney |
votes for Loebsack |
votes for Archer |
| Appanoose | 2,798 | 2,971 | 3,185 | 2,951 | 3,161 | 3,017 | 2,822 |
| Cedar | 3,310 | 3,720 | 4,854 | 4,972 | 4,529 | 5,021 | 4,220 |
| Clarke | 1,709 | 1,839 | 2,326 | 2,189 | 2,124 | 2,127 | 1,957 |
| Clinton | 11,533 | 7,441 | 13,460 | 15,141 | 9,432 | 13,743 | 9,750 |
| Davis | 1,967 | 1,567 | 1,485 | 1,520 | 2,138 | 1,851 | 1,822 |
| Decatur | 1,843 | 1,848 | 1,966 | 1,791 | 1,947 | 1,758 | 1,743 |
| Des Moines | 11,902 | 6,259 | 8,720 | 11,888 | 8,136 | 11,571 | 7,905 |
| Henry | 3,162 | 5,444 | 5,070 | 4,460 | 5,035 | 4,282 | 4,826 |
| Jasper | 9,126 | 7,365 | 8,020 | 10,257 | 8,877 | 10,043 | 8,328 |
| Jefferson | 3,569 | 3,626 | 3,593 | 4,798 | 3,436 | 4,784 | 3,281 |
| Johnson | 40,971 | 19,456 | 34,278 | 50,666 | 23,698 | 49,219 | 22,344 |
| Keokuk | 2,379 | 2,330 | 2,397 | 2,303 | 2,843 | 2,231 | 2,614 |
| Lee | 10,192 | 4,424 | 8,498 | 10,714 | 7,785 | 11,115 | 7,054 |
| Louisa | 1,946 | 2,520 | 2,658 | 2,452 | 2,420 | 2,301 | 2,346 |
| Lucas | 1,486 | 2,118 | 2,110 | 1,987 | 2,254 | 1,876 | 2,096 |
| Mahaska | 3,243 | 6,014 | 5,127 | 4,213 | 6,448 | 3,916 | 6,249 |
| Marion | 5,587 | 9,151 | 7,282 | 7,507 | 9,828 | 7,240 | 9,373 |
| Monroe | 1,821 | 1,541 | 1,586 | 1,731 | 2,026 | 1,762 | 1,819 |
| Muscatine | 8,032 | 8,332 | 10,662 | 11,323 | 8,168 | 10,727 | 7,994 |
| Scott | 36,175 | 30,621 | 46,059 | 50,652 | 38,251 | 46,734 | 38,605 |
| Van Buren | 1,095 | 2,207 | 1,680 | 1,402 | 2,064 | 1,547 | 1,864 |
| Wapello | 9,661 | 5,354 | 7,077 | 8,663 | 6,789 | 8,416 | 6,377 |
| Washington | 3,090 | 5,833 | 5,103 | 5,115 | 5,562 | 5,256 | 5,197 |
| Wayne | 1,065 | 1,408 | 1,203 | 1,251 | 1,583 | 1,326 | 1,391 |
| |
| total | 177,662 | 143,389 | 188,399 | 219,946 | 168,534 | 211,863 | 161,977 |
IA-03
Democrat Leonard Boswell finished well behind Obama in all sixteen counties, most disastrously in Polk, which the president carried by more than 32,000 votes. Polk was the sole county Boswell carried, and he only won it by about 4,000 votes. Every county in IA-03 delivered more votes to Republican Tom Latham than to Romney.
| County |
Democrats |
Republicans |
no-party voters |
votes for Obama |
votes for Romney |
votes for Boswell |
votes for Latham |
| Adair | 1,157 | 2,023 | 2,038 | 1,790 | 2,114 | 1,270 | 2,412 |
| Adams | 704 | 965 | 1,127 | 1,028 | 1,108 | 805 | 1,237 |
| Cass | 1,692 | 4,909 | 3,153 | 2,858 | 4,217 | 2,141 | 4,512 |
| Dallas | 10,727 | 16,662 | 17,986 | 20,988 | 16,576 | 12,842 | 23,033 |
| Fremont | 1,339 | 2,207 | 19,30 | 1,637 | 1,972 | 1,162 | 2,151 |
| Guthrie | 2,047 | 2,811 | 2,884 | 2,569 | 3,171 | 1,915 | 3,528 |
| Madison | 3,064 | 4,045 | 3,919 | 3,630 | 4,638 | 2,855 | 5,029 |
| Mills | 1,965 | 4,814 | 3,216 | 2,848 | 4,216 | 2,084 | 4,277 |
| Montgomery | 1,104 | 3,933 | 2,039 | 1,922 | 3,001 | 1,395 | 3,196 |
| Page | 1,719 | 4,484 | 3,688 | 2,612 | 4,348 | 2,172 | 4,477 |
| Polk | 106,424 | 83,732 | 82,405 | 128,465 | 96,096 | 109,508 | 105,234 |
| Pottawattamie | 16,604 | 21,270 | 18,962 | 19,644 | 21,860 | 15,815 | 22,384 |
| Ringgold | 915 | 1,467 | 747 | 1,186 | 1,368 | 1,037 | 1,421 |
| Taylor | 850 | 2,011 | 1,389 | 1,262 | 1,683 | 1,008 | 1,785 |
| Union | 1,854 | 2,881 | 3,071 | 3,043 | 2,813 | 2,422 | 3,157 |
| Warren | 10,059 | 10,739 | 10,897 | 12,551 | 13,052 | 10,201 | 14,167 |
| |
| total | 162,224 | 168,953 | 159,510 | 203,621 | 186,645 | 168,632 | 202,000 |
IA-04
Democrat Christie Vilsack only carried seven of the 39 counties in this district, but she came close to matching Obama's vote totals in 27 counties and outpolled the president in twelve counties: Butler, Cerro Gordo, Emmet, Floyd, Franklin, Hancock, Humboldt, Kossuth, Pocahontas, Shelby, Sioux, and Winnebago. King lagged a bit behind Romney in 28 counties but exceeded the GOP nominee's vote totals in nine counties: Carroll, Cherokee, Crawford, Ida, Monona, Osceola, Plymouth, Sac, and Woodbury.
| County |
Democrats |
Republicans |
no-party voters |
votes for Obama |
votes for Romney |
votes for Vilsack |
votes for King |
| Audubon | 1,332 | 1,618 | 1,422 | 1,611 | 1,802 | 1,531 | 1,757 |
| Boone | 5,556 | 5,678 | 6,953 | 7,512 | 6,556 | 7,303 | 6,374 |
| Buena Vista | 2,980 | 3,985 | 4,766 | 3,700 | 4,554 | 3,570 | 4,533 |
| Butler | 1,797 | 4,605 | 3,253 | 3,329 | 4,106 | 3,399 | 3,836 |
| Calhoun | 1,506 | 2,418 | 2,795 | 2,238 | 2,891 | 2,181 | 2,844 |
| Carroll | 4,241 | 4,064 | 6,354 | 4,947 | 5,601 | 4,577 | 5,749 |
| Cerro Gordo | 9,929 | 8,187 | 12,951 | 13,316 | 10,128 | 13,855 | 9,154 |
| Cherokee | 2,074 | 3,255 | 3,305 | 2,634 | 3,662 | 2,415 | 3,775 |
| Chickasaw | 3,003 | 2,211 | 3,714 | 3,554 | 2,836 | 3,504 | 2,692 |
| Clay | 2,685 | 4,619 | 4,542 | 3,385 | 4,951 | 3,315 | 4,860 |
| Crawford | 2,834 | 3,160 | 3,512 | 3,066 | 3,595 | 2,618 | 3,913 |
| Dickinson | 2,680 | 5,268 | 4,711 | 4,095 | 5,912 | 3,968 | 5,819 |
| Emmet | 2,238 | 1,746 | 3,188 | 2,099 | 2,507 | 2,113 | 2,384 |
| Floyd | 3,216 | 2,743 | 4,759 | 4,680 | 3,472 | 4,704 | 3,256 |
| Franklin | 1,340 | 3,108 | 2,322 | 2,266 | 2,823 | 2,314 | 2,703 |
| Greene | 2,059 | 2,149 | 2,347 | 2,375 | 2,380 | 2,283 | 2,364 |
| Grundy | 1,487 | 4,119 | 3,042 | 2,635 | 4,215 | 2,573 | 4,074 |
| Hamilton | 2,844 | 3,617 | 3,789 | 3,782 | 3,991 | 3,689 | 3,924 |
| Hancock | 1,651 | 3,319 | 2,957 | 2,521 | 3,317 | 2,559 | 3,131 |
| Hardin | 2,829 | 4,700 | 4,107 | 4,075 | 4,670 | 3,890 | 4,637 |
| Harrison | 2,575 | 3,655 | 2,689 | 3,136 | 4,065 | 2,999 | 3,937 |
| Humboldt | 1,388 | 2,498 | 2,496 | 1,972 | 3,099 | 1,983 | 2,958 |
| Ida | 975 | 2,177 | 1,951 | 1,321 | 2,286 | 1,131 | 2,440 |
| Kossuth | 3,569 | 3,484 | 4,273 | 3,850 | 4,937 | 4,026 | 4,584 |
| Lyon | 915 | 5,478 | 1,746 | 1,423 | 4,978 | 1,416 | 4,783 |
| Monona | 2,132 | 1,926 | 2,491 | 2,101 | 2,557 | 1,876 | 2,698 |
| O'Brien | 1,412 | 5,345 | 2,869 | 1,969 | 5,266 | 1,869 | 5,237 |
| Osceola | 551 | 2,614 | 1,139 | 912 | 2,230 | 833 | 2,242 |
| Palo Alto | 2,461 | 1,635 | 2,280 | 2,139 | 2,660 | 2,115 | 2,561 |
| Plymouth | 3,426 | 8,022 | 5,979 | 4,164 | 8,597 | 3,973 | 8,615 |
| Pocahontas | 1,132 | 1,703 | 2,210 | 1,518 | 2,388 | 1,530 | 2,339 |
| Sac | 1,422 | 3,146 | 2,640 | 2,122 | 3,094 | 1,784 | 3,362 |
| Shelby | 2,135 | 3,733 | 2,975 | 2,469 | 3,911 | 2,491 | 3,637 |
| Sioux | 1,703 | 14,686 | 3,870 | 2,700 | 14,407 | 2,777 | 14,111 |
| Story | 17,513 | 16,604 | 22,259 | 26,192 | 19,668 | 26,161 | 18,493 |
| Webster | 9,067 | 6,911 | 9,013 | 9,537 | 8,469 | 9,388 | 7,995 |
| Winnebago | 1,628 | 3,046 | 2,723 | 2,903 | 2,906 | 2,953 | 2,722 |
| Woodbury | 19,844 | 19,504 | 19,731 | 22,302 | 21,841 | 21,077 | 22,313 |
| Wright | 1,990 | 3,570 | 2,755 | 2,836 | 3,349 | 2,727 | 3,257 |
| |
| total | 134,119 | 184,306 | 180,878 | 173,386 | 204,677 | 169,470 | 200,063 |
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