Electoral college - all you need to know

Updated on 04 November 2008

The USA picks its president through a state-by-state electoral college system.

This can give a different result from the overall national majority vote.

The electoral college is part of the original design of the US constitution - although some details were amended in 1804. Technically, voters choose electors, who in turn vote on behalf of the state, rather than directly picking a candidate.

The bigger the state, the more electoral college votes it gets.

Jon Snow explains all

Votes are allocated to different states based on how many senators (always two) and representatives (dependent on the state's population) each sends to congress.

Each state gets a minimum of three votes, as does the District of Columbia. California, the biggest state, gets 55 votes.

In total, there are 538 electoral college votes - representing 100 members of the senate (two per state), 435 members of the house of representatives, plus three for the District of Columbia.

Votes within a state

In all but two of the states, whichever candidate comes top receives all of the electoral college votes for that state. The only exceptions to this are Nebraska and Maine, which allocate votes proportionately.

The winner-takes-all system means the big states assume great importance.

Topping the polls in California - even if it's only by a fraction of a percentage point - automatically swings 55 votes the candidate's way. Storming home by a mile in Delaware or Wyoming only counts for three votes.

Winning all 10 of the biggest states would give the candidate 256 votes - just 14 shy of the 270 needed to run the country.

The national popular vote isn't necessarily reflected in the results of the electoral college - meaning candidates keep a close eye on polling in key states in the run-up to election day.