Two-party system
A two-party system is a party system where two major political parties dominate the government. One of the two parties typically holds a majority in the legislature and is usually referred to as the "majority" or "governing party" while the other is the "minority" or "opposition party". Around the world, the term has different senses. For example, in the United States, Jamaica, and Malta, the sense of "two-party system" describes an arrangement in which all or nearly all elected officials belong to one of the only two major parties, and third parties rarely win any seats in the legislature. In such arrangements, two-party systems are thought to result from various factors like winner-takes-all election rules. In such systems, while chances for third-party candidates winning election to major national office are remote, it is possible for groups within the larger parties, or in opposition to one or both of them, to exert influence on the two major parties. In contrast, in the United Kingdom and Australia and in other parliamentary systems and elsewhere, the term "two-party system" is sometimes used to indicate an arrangement in which two major parties dominate elections but in which there are viable third parties which do win seats in the legislature, and in which the two major parties exert proportionately greater influence than their percentage of votes would suggest.
Politics of the United States
Since the 1790s, the country has been run by two major parties, beginning with the Federalist vs. the Democratic-Republicans, then the Whigs vs. the Democrats, and now the Democrats and Republicans. Minor or third political parties appear from time to time and tend to advocate for policies dedicated to a specific issue. At various times the Socialist Party, the Farmer-Labor Party and the Populist Party for a few years had considerable local strength, and then faded away—although in Minnesota, the Farmer–Labor Party merged into the state's Democratic Party, which is now officially known as the Democratic–Farmer–Labor Party. At present, the Libertarian Party is the most successful third party. New York State has a number of additional third parties, who sometimes run their own candidates for office and sometimes nominate the nominees of the two main parties. In the District of Columbia, the D.C. Statehood Green Party has served as a strong third party behind the Democratic Party and Republican Party.