Watch Live Monday: USA Today Iowa Caucus coverage

For 50 years, Iowans have gathered in school gymnasiums, community centers and family living rooms to kick off the nation's presidential nominating process, wielding their outsized influence to winnow and shape the field of contenders. Ahead of each caucus, presidential candidates flood the state for months, if not years, to try to woo Iowans and gain their support. The national and international media descends on the state, ready to derive meaning from caucus night results.