Political Parties

Political Parties and the Two-Party System

By the end of this lesson, you will be able to describe the functions of political parties, explain why the US has a two-party system, and trace the major party realignments in US history.

What Parties Do

Six functions of political parties:

1. Recruit and nominate candidates for office — the primary function that distinguishes parties from interest groups
2. Mobilize voters — register voters, run GOTV (get out the vote) campaigns
3. Organize government — the majority party controls committee chairs, floor schedules, leadership positions
4. Define policy positions — party platforms signal what the party stands for
5. Link citizens to government — provide voting cues; simplify political information
6. Provide loyal opposition — the minority party critiques the majority and offers alternatives

Why a Two-Party System?

Duverger's Law: in single-member, plurality-based electoral systems (winner-take-all), two dominant parties tend to emerge. Third parties cannot win — coming in second wins nothing — so voters rationally consolidate behind the two most viable parties.

Other factors:

• Ballot access laws favor established parties
• Campaign finance and media access favor major parties
• Voters fear "wasting" their vote on a third party

Historical third party role: third parties rarely win, but they introduce ideas that the major parties eventually adopt (Populists in the 1890s → Democratic policies in the 1930s; Reform Party → immigration debates in the 2000s).

Party Realignments: The Party System Eras

First party system (1790s–1820s): Federalists vs. Democratic-Republicans. Collapsed with the "Era of Good Feelings."

Second party system (1824–1854): Democrats vs. Whigs. Slavery destroyed the Whig Party.

Third party system (1854–1896): Republicans vs. Democrats. Civil War era; Republicans dominated after the war.

Fourth party system (1896–1932): Republicans dominant after 1896 realignment; business and industry era.