Primary elections in the United States are used to choose one candidate from a pool of applicants for each political party to run in an election as a representative of the entire party.
Presidential Primary Election
A primary is conducted in an electoral party system to elect a presidential and, usually, a vice-presidential representative to run in the national election. Typically, you must be registered with a party to vote in its primaries. There are usually 3 to 5 candidates for each party who slowly drop out as they lose support in the polls before the voters choose the individual they believe will best represent them as citizens (support their issues).
In elections that are not divided by political party, primaries are often held simply to narrow down a pool of candidates prior to the election of one individual. In the United States, these include municipal and county offices or appointed positions.
U.S. Presidential Primary Process
Primary elections are held in the states over a period of about a month. Iowa and New Hampshire notably hold the earliest primaries. Voters go to the polls and choose the candidate they would like their delegates to represent. Often the winner is presumed well before the last state primaries, but this is not always the case. Both parties then hold national conventions in which the single representative for president is declared. This representative and other important members of the party give speeches about important issues to their constituents.
History of U.S. Primary Elections
Prior to 1820, members of Congress chose their party representatives for the presidential election. The first primaries were held in 1832, but the process was not perfected until the early 20th century when states (beginning with Oregon) massed measures that required the chosen delegates to vote in the interest of the constituents. Otherwise, the delegates could be influenced by bribes or favors to change their vote at the last minute. Furthermore, in the early 20th century, primaries were a notable method of limiting the voting rights of African-Americans. As many states use a closed party system--meaning only those registered with a particular party can vote in them, and African-Americans were barred from registering with a party--African-Americans could not vote in primaries. The 1944 Supreme Court decision of Smith vs. Allwright declared the barring unconstitutional.
Criticism of Primary Elections
Critics of the two-party system in the Unites States claim that the primary election process and the resulting two candidates limit the choices available to voters who feel obligated to side with one party or the other, in effect, choosing the best of two evils. Furthermore, with campaigning beginning well before the first state primary, the funds spent on a candidate's campaign are astronomical and largely funded by the public.