Often as a cause of two-party system in the US cited the first-past-the-post system. (see also Duverger's Law). But theoretically this should not prevent having strong local state-level parties.

It seems that the political life in the US would be richer if it had several tens of locally strong parties, even if only two parties would participate in presidential elections.

Or, maybe, the cause is because the Americans cannot be members of two parties at the same time, so that if you are a member of a local party, you are excluded from Democrat and Republican primaries?

  • 4
    @JoeW, why not. The UK has local parties: Sinn Fein, DUP, SNP, Plaid Cymru.
    – James K
    Aug 27, 2023 at 7:13
  • 3
    Two possible factors: there are no significant independentist movements (except in Puerto Rico) and US political parties are more loosely coupled than European political parties, meaning that an US Senator from North Dakota could be very active in promoting ND interest even against his own party line.
    – SJuan76
    Aug 27, 2023 at 7:48
  • 1
    Whether a candidate can be listed on the ballot under multiple parties is determined by state law. It is allowed in New York, at least.
    – phoog
    Aug 27, 2023 at 12:03
  • 4
    @JoeW, yes of course, but that's for national elections. There is no reason why the state legislature of North Dakota should be dominated by the same two parties that dominate national politics. . . Take India, for example. Congress and the BJP dominate national politics, but these aren't the big parties in Kerala, where the UDF and LDF alternate power. The communist party doesn't have a chance at federal level in India, but it wins at the state level in Kerala.
    – James K
    Aug 27, 2023 at 19:20
  • 1
    Minnesota has distinctive politics with the Minnesota Democratic–Farmer–Labor Party and Reform Party. Vermont has its quirks too. I'm not sure what qualifies as regional and what doesn't - parties can have regional strongholds but stand candidate in other areas.
    – Stuart F
    Aug 28, 2023 at 10:11

3 Answers 3


In U.S. electoral politics, federal electoral offices and state and local electoral offices have become institutionally entwined with each other, although some cities with officially non-partisan elections (e.g. Glendale, Colorado) have developed unofficial political parties not aligned with the national parties. In part, this is because the federal government has come to play such a dominant role in American federalism.

This doesn't happen in Puerto Rico, however, because Puerto Rico has no participation in elections for any federal offices.

  • 1
    Additionally, the platforms of the Puerto Rican parties seem centered on how to frame the island's status vis-a-vis of the US. That's prolly something that's not clearly connected to the usual ideological divides in the rest of the US. Although the PPD is affiliated with the Democrats, the PNP seems more split. Sep 2, 2023 at 10:25

The voting system in Puerto Rico is different than that used in US states. It is that difference that allows for smaller parties to gain seats in the legislature.

The voting system in Puerto Rico is a mixed system using plurality-at-large for a fixed number of senate seats, first-past-the-post for a fixed number of house seats, and single non-transferable-vote for at-large seats for both the senate and house. See, Electoral system for Puerto Rico.

The Senate of Puerto Rico currently has 27 members, including 16 members elected from 8 two-seat electoral districts through plurality at large (each Senate district comprises 5 House districts), plus 11 at-large members. The House of Representatives of Puerto Rico currently (2019) has 51 members composed of 40 members elected in single-seat electoral districts using first-past-the-post, plus 11 at-large members.

In each house, 11 at-large members are elected from an island-wide district based on single non-transferable vote. To avoid vote splitting, the two major parties will typically nominate only 6 members and smaller parties typically only nominate one. Additionally, parties may choose the ballot order of its candidates in different districts, in an attempt to signal to voters the preferred method of voting. However, each voter is free to choose any candidate.

  • Meh, despite different system, the HoR of Puerto Rico is clearly dominated by two parties together having 45 out of 51 seats. The other parties have 1-2 seats each. So this isn't a compelling answer. Sep 2, 2023 at 10:50

The US two party system is supported not only by the first-past-the-post system but also by the fact that the two main parties are huge fundraising engines, unfettered by the campaign finance rules applied in other countries. Those parties transfer funds to any seat where there is a strong challenge, such as a significant local party.

Since the bigger national parties can almost always outspend the smaller local parties the latter rarely win. This means that any politician or local interest group is almost always better off aligning with one of the big parties than forming a separate local party, and working to advance local interests from within the national party.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .