The United States is a democracy with a republican form of government. The country belongs to the American people, including voters who register without affiliating with any political party. Elected officials represent all voters in government, and although election methods vary by state, the process usually begins with a primary election. The winners of primary elections face their opponents in a general election. Unaffiliated or independent voters cannot vote in some primaries.

Primary Elections Defined

Beyond certain federal restrictions, individual states control the entry of candidates on election ballots. In some elections, independent voters who register without affiliating with any political party cannot vote in a primary election, while in other states they can. The Republican and Democratic parties dominate the American political system. Rules for the electoral process are geared toward maintaining their power. Although a 2011 Gallup poll reported that over 40 percent of American voters registered as independents, the two parties monopolize political office at all levels of government.

Closed Primaries

Several forms of primary elections exist among the states. Many are "closed primaries," meaning only registered members of a party may vote. They must use ballots listing only the names of those representing the voters' registered party affiliation. Independent and unaffiliated voters cannot vote in closed primaries. According to FairVote.com, 18 states have closed primaries, while in five others only the Republican Party primary is closed.

Open Primaries

In 19 states, primaries are open to voters of any affiliation, and in two others, only the Democratic primary is open. Independent voters may vote, but only in the primary of one party. Open primaries pave the way for "crossover voting," in which voters of one party may try to influence the nomination of an opposing party.

In seven states, a form of open primary called "semi-closed" prevents crossover voting by allowing only registered independent voters to vote in either primary. In three other states only the Democrats have semi-closed primaries. In most open primaries, voters must declare their party affiliation at the polls.

Top-two Primaries

Washington and California put the names of all candidates on the same ballot, rendering party affiliation irrelevant during primary elections. Nebraska holds this type of primary for state legislative offices while Louisiana holds a second run-off election when a candidate fails to gain more than 50 percent of the primary vote. The two candidates with the most votes compete in the general election. Any registered voter, including independents, can vote in this form of open election.