A poll worker hands out "I Voted Today" stickers in Washington, D.C., in 2012. Journalist Ari Berman says a 2013 Supreme Court ruling opened the door for new voting restrictions that disproportionately affect poor people, young people and people of color. Brendan Smialowski/AFP/Getty Images hide caption

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People wait in line outside the Supreme Court in Feb. 2013 to listen to oral arguments in the Shelby County, Ala., v. Holder voting rights case. Evan Vucci/AP hide caption

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Election Day volunteer Vicki Groff places a sign to direct voters to a polling station at Kenilworth School in Phoenix in 2012. Jonathan Gibby/Getty Images hide caption

itoggle caption Jonathan Gibby/Getty Images