Illinois is about to become the 16th state to legalize gay marriage.
It started when the state legislature passed the marriage equality bill on November 5.
Today, more than 3,000 people are expected to witness Governor Quinn signing it into law at the UIC forum.
Illinois has had civil unions for about three years.
But after June first, gay couples can earn the benefits of being legally married.
The gay marriage bill is expected to be a boost for the wedding industry.
Researchers estimate gay marriages could bring $103 million to the state over the next three years.