by tradition which state’s caucus is the first presidential contest held every four years
United States presidential primary The first binding event, in which a candidate can secure convention delegates, is traditionally the Iowa caucus, usually held in late January or early February of the presidential election year. It is generally followed by the New Hampshire primary, the first primary by tradition since 1920 and by New Hampshire state law. New Hampshire law states the primary shall be held "on the Tuesday at least seven days immediately preceding the date on which any other state shall hold a similar election." The Iowa caucuses are not considered to be "a similar election" under New Hampshire's law because the former uses caucuses instead of primary elections. Should any other state move its primary too close to New Hampshire's, or before, the New Hampshire Secretary of State is required to reschedule the primary accordingly.[34]
United States presidential election Presidential elections occur quadrennially with registered voters casting their ballots on Election Day, which since 1845 has been the first Tuesday after November 1.[2][3][4] This date coincides with the general elections of various other federal, state, and local races; since local governments are responsible for managing elections, these races typically all appear on one ballot. The Electoral College electors then formally cast their electoral votes on the first Monday after December 12 at their respective state capitals. Congress then certify the results in early January, and the presidential term begins on Inauguration Day, which since the passage of the Twentieth Amendment has been set at January 20.