M. Spencer Green / AP Illinois Gov. Pat Quinn acknowledges the applause after signing the Religious Freedom and Marriage Fairness Act into law, making Illinois the 16th state in the nation to embrace full marriage equality for same sex couples, on Nov. 20, in Chicago, Ill.

Illinois became the 16th state in the country to legalize same-sex marriage Wednesday.

A massive audience crowded into the University of Illinois at Chicago Forum to see Democratic Gov. Pat Quinn sign marriage equality legislation — on the same desk President Abraham Lincoln used to pen his first inaugural address.

"Love never fails," Quinn said amid thunderous applause, immediately before sitting down to put his signature on the historic law.

Several officials delivered passionate and celebratory remarks ahead of the signing.

"It's time to stop planning rallies and start planning weddings," said Lt. Gov. Sheila Simon to loud cheers.

State Rep. Greg Harris, a primary sponsor of the bill who is openly gay, applauded activists and advocates who lobbied for the legislation.

"Ladies and gentlemen, this was a labor of love and it was a mammoth undertaking," Harris said.

The legislation — officially named SB10, the Religious Freedom and Marriage Fairness Act — passed both houses of the state legislature in early November and was delivered to Quinn on Nov. 6, according to the Illinois General Assembly.

It is slated to take effect June 1, 2014.

As advocates celebrated in Chicago, Bishop Thomas John Paprocki of the Roman Catholic Diocese of Springfield, Ill recited “prayers of supplication and exorcism” in opposition to the “sin” of same-sex nuptials.

When asked if Paprocki’s homily reflects the views of the diocese, spokeswoman Kathie Sass said: “It reflects the teachings of the Catholic Church.”

When reached for comment, United States Conference of Catholic Bishops spokesman Don Clemmer said the body "does not comment on diocesan events."

The Land of Lincoln now joins 15 other states, plus the District of Columbia, that allow same-sex marriages — nearly double the number at this time last year.

Illinois couples who had previously joined in civil unions, which were approved in the state in 2010 and began in mid-2011, will be able to have that legal relationship converted into marriage. They have one year to make the change, and typical marriage fees will be waived, according to the legislation.

Thirty-four states prohibit same-sex marriage. Many of those state bans also face legal challenges, with nearly 30 lawsuits filed across the country after two Supreme Court decisions in the summer that favored gay marriage rights.

Lincoln's desk was transported to Chicago for the signing ceremony from the Lincoln-Herndon Law Office in Springfield, according to the Associated Press.

NBC News' Miranda Leitsinger and Matthew DeLuca, as well as the Associated Press, contributed to this report.

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