<P> The most common method used in U.S. elections is the first - past - the - post system, where the highest polling candidate wins the election . Some may use a two - round system, where if no candidate receives a required number of votes then there is a runoff between the two candidates with the most votes . </P> <P> Since 2002, several cities have adopted instant - runoff voting in their elections . Voters rank the candidates in order of preference rather than voting for a single candidate . If a candidate secures more than half of votes cast, that candidate wins . Otherwise, the candidate with the fewest votes is eliminated . Ballots assigned to the eliminated candidate are recounted and assigned to those of the remaining candidates who rank next in order of preference on each ballot . This process continues until one candidate wins by obtaining more than half the votes . </P> <P> The eligibility of an individual for voting is set out in the constitution and also regulated at state level . The constitution states that suffrage cannot be denied on grounds of race or color, sex, or age for citizens eighteen years or older . Beyond these basic qualifications, it is the responsibility of state legislatures to regulate voter eligibility . Some states ban convicted criminals, especially felons, from voting for a fixed period of time or indefinitely . The number of American adults who are currently or permanently ineligible to vote due to felony convictions is estimated to be 5.3 million . Some states also have legacy constitutional statements barring legally declared incompetent from voting; such references are generally considered obsolete and are being considered for review or removal where they appear . </P> <P> While the federal government has jurisdiction over federal elections, most election laws are decided at the state level . All U.S. states except North Dakota require that citizens who wish to vote be registered . Traditionally, voters had to register at state offices to vote, but in the mid-1990s efforts were made by the federal government to make registering easier, in an attempt to increase turnout . The National Voter Registration Act of 1993 (the "Motor Voter" law) required state governments that receive certain types of federal funding to make the voter registration process easier by providing uniform registration services through drivers' license registration centers, disability centers, schools, libraries, and mail - in registration . Other states allow citizens same - day registration on Election Day . </P>

Who sets voting qualifications on the state level