The vote in the Vermont House of Representatives was a nail-biter: Lawmakers tossed Gov. Jim Douglas’ veto of legislation allowing gay marriage by a single vote, 100-49, with a two-thirds majority required to quash the veto. Earlier Tuesday, the Vermont Senate overrode the veto 23-5.

Here’s video coverage of the crucial Vermont vote from The Burlington Free Press:

There are now four states — Massachusetts and Connecticut, in addition to Iowa and Vermont — that have legalized same-sex weddings. Last year, the California Supreme Court legalized gay marriage, but a ballot initiative struck down the ruling.

Colorado voters passed an amendment to the state constitution in 2006 that forbids gay marriage, but two groups are mounting ballot proposals intended to reverse the ban next year. Yesterday, The Colorado Independent pointed to a statistical analysis by Nate Silver of FiveThirtyEight.com that suggests Colorado voters could be ready to establish the right gay marriage in 2010.