Illinois Governor Pat Quinn and Chicago Mayor Rahm Emanuel will attend a June 2 event celebrating the civil unions of 30 gay and lesbian couples.

“Our state's first civil union ceremonies will mark a day of celebration and an historic milestone on the road to full marriage equality for LGBT Illinoisans,” Emanuel said. “I look forward to attending this joyful event.”

Illinois' new civil unions law comes into force on June 1, but a one-day waiting period makes Thursday, June 2 the first day couples can exchange vows. The state's law gives gay couples most of the benefits of marriage.

The ceremonies will take place in Chicago's downtown Millennium Park and is being hosted by the city's Advisory Council on Lesbian, Gay, Bisexual and Transgender Issues, the Chicago Tribune reported.

Lawmakers approved the legislation in December and Quinn signed the bill into law in January.

The 30 couples will apply for their civil unions licenses from the Cook County clerk's office on Wednesday, June 1 and tie the knot the following day.

The Honorable Timothy C. Evans, Chief of the Circuit Court of Cook County, along with members of the Alliance of Illinois Judges will officiate the civil union ceremonies.

At the start of 2010, only New Jersey offered the union after New Hampshire and Vermont upgraded gay couples to marriage. Illinois, Hawaii and Delaware have since joined in legalizing the union. A similar bill in Colorado died in committee.

Gay marriage advocates in Rhode Island are fuming over House Speaker Gordon Fox's recent decision to back civil unions legislation over marriage for gay couples.

Washington, California, Nevada and Oregon grant similar benefits to gay couples with domestic partnerships.