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The first-past-the-post electoral system is a voting system for single-member districts, variously called first-past-the-post (FPTP)), winner-take-all, plurality voting, or relative majority. In political science, it is known as Single-Member District Plurality or SMDP. This system is in use at all levels of politics; it is very common in former British colonies. For a thorough list, see below.

Procedures

Each voter selects one candidate. All votes are counted and the candidate or option with the most votes is the winner.

An example

Imagine an election for the capital of Tennessee, a state in the United States that is over 500 miles east-to-west, and only 110 miles north-to-south. Let's say the candidates for the capital are Memphis (on the far west end), Nashville (in the center), Chattanooga (129 miles southeast of Nashville), and Knoxville (on the far east side, 114 northeast of Chattanooga). Here's the population breakdown by metro area (surrounding county):

• Memphis (Shelby County): 826,330
• Nashville (Davidson County): 510,784
• Chattanooga (Hamilton County): 285,536
• Knoxville (Knox County): 335,749

Let's say that in the vote, the voters vote based on geographic proximity. Assuming that the population distribution of the rest of Tennesee follows from those population centers, one could easily envision an election where the percentages of sincere preferences would be as follows:

If voting follows sincere preferences, Memphis is selected with the most votes. Note that this system does not require that the winner have a majority, but only a plurality. That is, Memphis wins because it has the most votes, even though more than half of the voters preferred another option.

Potential for tactical voting

First-past-the-post encourages the tactical voting technique known as "compromising": voters are encouraged to vote for one of the two options most likely to win, even if it is not their most preferred option. In the above example, voters from Chattanooga and Knoxville may "compromise" by voting for Nashville, which they prefer to Memphis.

Anomalous results

An interesting anomaly in the results of this system arose in the Canadian federal election of 1926 for the province of Manitoba. The province was entitled to 17 seats in that election. The percentage of votes received across the province were

• Conservatives 42.2%
• Labour Progressives 19.5%
• Liberals 18.4%
• Progressives 11.2%
• Labour 8.7%

The apportionment of seats however was

• Conservatives 0
• Labour Progressives 7
• Liberals 4
• Progressives 4
• Labour 2

The Conservatives clearly had the largest number of votes across the province, but received no seats at all. The other parties were able to have success by having concentrated support in particular constituencies.

Duverger's law

Because of these anomalies and the tactical-voting tendencies, Duverger's law predicts that constituencies that use first-past-the-post systems will become two-party systems.

Where it's used

Countries that use this system to elect the lower or only house of their legislature:

Bahamas -- Bangladesh -- Barbados -- Belize -- Botswana -- Canada -- Dominica -- The Gambia -- Grenada -- Jamaica -- Federated States of Micronesia -- Nepal -- Papua New Guinea -- Saint Kitts and Nevis -- Saint Lucia -- Saint Vincent and the Grenadines -- Samoa -- Solomon Islands -- Trinidad and Tobago -- United Kingdom (Westminster elections) -- United States -- Zambia

see Table of voting systems by nation

The first past the post election system is used in the Republic of China on Taiwan for executive offices such as county magistrates, mayors, and the president, but not for legislative seats which used the single non-transferable vote system. This has produced an interesting party structure in which there are two broad coalitions of parties which cooperate in executive elections but which compete internally in legislative elections.

Source: Making Votes Count, Gary Cox (1997)

External links

• ACE Project: First Past The Post - Detailed explanation of first-past-the-post voting