MONTPELIER – Vermont has become the fourth state in the country to allow same-sex couples to marry.

Lawmakers voted Tuesday morning to override Gov. James Douglas’ veto of the bill, with a narrow victory in the Vermont House paving the way for the state to become the first to allow same-sex marriage without a court order.

The move comes nine years after Vermont made history by legalizing civil unions for same-sex couples. Now, it joins a landscape that includes Massachusetts, Connecticut and Iowa as the only states allowing gay and lesbian couples to marry.

“We are not done yet until every lawmaker who voted yes gets 1,000 thank you cards,” proclaimed Beth Robinson, an attorney with the group Vermont Freedom to Marry during a Statehouse victory rally after the vote. “We’re not done yet until every person who voted for this is reelected in 2010.”

Tears of joy broke out among the large crowd of supporters at the Statehouse after the final vote was announced around 11 a.m. Couples hugged, congratulated supportive lawmakers and began planning for wedding ceremonies in the fall.

Same-sex couples are expected to begin marrying on Sept. 1, the date the law takes effect.

Senators easily overrode the Republican governor’s veto in a morning vote of 23-5. The vote in the House was more dramatic: 100 members voted to override and 49 voted to sustain the veto. A two-thirds majority is needed to override a veto.

Rev. Nancy Vogel of Saint Paul’s Episcopal Church in White River Junction, who served on a legislative commission to study same-sex marriage last year, said some surprise votes on the House floor and one missing Democrat made her nervous that it would not pass.

“I was just so afraid that we wouldn’t get those 100 votes we needed,” said Vogel, who was joined in a civil union with her partner, Cheryl Elinsky, five years ago. “But now we’re planning for a Sept. 1 wedding.”

Contact Daniel Barlow at Daniel.Barlow@timesargus.com.