How did George Bush win the 2000 election despite losing popular vote?

The US Presidential election of 2000 was as close as any in US history. Democratic candidate (former vice-president) Al Gore trailed in the vote count to George W. Bush in the pivotal state of Florida, and whichever candidate won Florida would win the election.

The controversy came about because of the voting methods in the state, which varied by county, and because of differences in the way ballots were tallied. In some cases, some "punch card" ballots were not counted because the hole failed to completely open ("the dimpled chad" or "the hanging chad"). County election officials could only examine these manually because the counting machines would not record them. In some cases, the intent of the voter could still not be conclusively determined.

Because of this inconsistency, Democratic Party officials sued to require manual recounts in Florida counties that appeared to have the most uncounted votes. This was opposed by the Republican Party (Bush had a narrow lead in the totals). Although the Florida Supreme Court voted to recount, this was blocked by the US Supreme Court, and George W. Bush won Florida, and the Presidency.

The debate was never settled, but moves were made in Florida to establish definitive rules for counting votes, as well as establishing more reliable voting methods.