The group publicly released a letter Sunday that'll be sent to lawmakers this week. It says allowing same sex couples to marry would generate between $39 million and $72 million in revenues for Illinois businesses.
Those who've signed include the heads of Navistar International, Johnson Publishing and Morningstar Inc., along with the heads of restaurants and hotels.
Lawmakers did not take up legalizing gay marriage during the lame-duck session which ended last week before new lawmakers were sworn in. The legislation would offer same-sex couples marriage rights now only available to heterosexual couples.
Several religious groups oppose allowing same-sex marriage in Illinois calling it "dangerous" to religious freedom.