Michigan Rep. John Conyers, at a congressional hearing last week. The Democrat and longtime congressman faces the prospect of not being on Michigan's August primary ballot after failing to present the required number of valid signatures. Carolyn Kaster/AP hide caption

itoggle caption Carolyn Kaster/AP

Rep. John Dingell, D-Mich., the longest-serving member of Congress, is celebrated by colleagues, including Vice President Biden, on Capitol Hill in June 2013. A former chairman of the Energy and Commerce Committee, Dingell, now 87, announced in February that he will retire after this term. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

Michigan Attorney General Bill Schuette speaks to reporters after arguing the case before the U.S. Supreme Court in October. He's with XIV Foundation CEO Jennifer Gratz, who was a plaintiff in a lawsuit against the University of Michigan's affirmative action policy. Susan Walsh/AP hide caption

itoggle caption Susan Walsh/AP

Michigan Gov. Rick Snyder is pushing for changes to federal law to allow more skilled immigrants into the country. Snyder, a Republican, has proposed funneling 50,000 skilled immigrants into Detroit over five years as a way to rejuvenate the moribund city. Paul Sancya/AP hide caption

itoggle caption Paul Sancya/AP

Henry Ford Hospital treats Detroit residents. About 1 in 3 residents of that city is uninsured, and the hospital CEO hopes Medicaid expansion will increase the number of people with health insurance. Eric Whitney hide caption

itoggle caption Eric Whitney

Ripe Gala apples are ready for picking at an orchard in South Haven, Mich. spablab/Flickr.com hide caption

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Whenever a steer or cow leaves a farm in Michigan or goes to a slaughterhouse, it passes by a tag reader, and its ID number goes to a central computer that keeps track of every animal's location. Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR

Republican presidential candidate Mitt Romney makes a pie shell with store owner Linda Hundt during a campaign stop Tuesday in DeWitt, Mich. Joe Raedle/Getty Images hide caption

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Following a visit to his Michigan campaign headquarters on Feb. 28, Mitt Romney told reporters that Republican voters should choose the party's nominee. Justin Sullivan/Getty Images hide caption

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In a final bit of campaigning before Tuesday's vote, Mitt Romney and his wife, Ann, wave to his supporters during a campaign stop in Royal Oak, Mich., on Monday night. Rebecca Cook /Reuters /Landov hide caption

itoggle caption Rebecca Cook /Reuters /Landov

Polls show Rick Santorum and Mitt Romney in a tight race heading into Tuesday's Michigan primary. Santorum's campaign signs are stuck in the snow before his campaign stop at the The Colonial Valley Suites on Feb. 26 in Davison, Mich. Joe Raedle/Getty Images hide caption

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GOP presidential candidate Fred Karger hopes Michigan's primary rules will allow him to pick up a few delegates to the national convention. He's focusing on just one congressional district in the center of the state. Rick Pluta for NPR hide caption

itoggle caption Rick Pluta for NPR