The D.C. Council approved a bill to legalize same-sex marriage today by an eleven-to-two vote.

The bill, which will move on to D.C. Mayor Adrian M. Fenty, must stand through a 30-day legislative review period before it becomes law. If it survives, same-sex marriage will be legal next spring. In order for the bill to fail, the President, and Congress would need to sign a disapproval resolution during the 30-day review period, but same-sex marriage advocates are optimistic.

“We believe we are firmly rooted in the right side of history, and I know we are going to prevail, but we are going to have to remain vigilant to protect this right,” gay council member David A. Catania told the “Washington Post “.

If the bill sticks, D.C. will become the first city below the Mason-Dixon line to approve same-sex marriage.