U.S. political parties select candidates for president and vice-president through a series of local caucuses and state-wide primaries in which voters cast secret ballots, culminating in national conventions.On Monday at seven in the evening, tens of thousands of Democrats in Iowa will gather in schools, gymnasiums, churches and libraries, in all 1,678 precincts of the state, to select which of the presidential candidates they support.https://www.graphicnews.com/en/pages/39931/us-election-road-to