Thirty-six same-sex couples tied the knot Thursday at a high-profile public ceremony in Chicago's Millennium Park, a day after the newly-signed Illinois Religious Freedom Protection and Civil Union Act that allows such marriages became effective.

A judge (L) signs a certificate for a lesbian couple during a wedding ceremony held by the City of Chicago Commission on Human Relations' Advisory Council on Lesbian, Gay, Bisexual and Transgender Issues, in Chicago, the United States, June 2, 2011. Four months after Governor Pat Quinn signed the legislation recognizing same-sex unions, the U.S. state of Illinois opened its doors to gay partners seeking official state recognition on Wednesday. [Jiang Xintong/Xinhua]

"This is indeed a historic day, a special day, a day that all of us in the Land of Lincoln can all celebrate," Illinois Governor Pat Quinn, a Democrat, declared prior to the event. "We believe that everybody's in, and nobody's left out in our state. Everybody is important."

Quinn, who signed the law in January, called the legislation "one of the most important bills that Illinois has passed in anyone's memory."

The law took effect Wednesday, but it requires all same-sex couples to wait one day before holding a ceremony, which means that Thursday, June 2, is the first day such ceremonies can be performed in the state.

Chicago Mayor Rahm Emanuel, also a Democrat, gave his blessings to the same-sex couples at the scene.

"It's been a long journey here," he said. "To all those who are about to get married and join in civil union, you have a fruitful journey going forward. You have our blessings."

Same-sex marriages are still banned in most parts of the United States, and besides Illinois, only Connecticut, Iowa, Massachusetts, New Hampshire and Vermont plus Washington D.C. allow civil unions or their equivalent.

At federal level, the U.S. Defense of Marriage Act prohibits same-sex couples from receiving benefits, like tax breaks and immigration rights of foreign partners.