Google, Groupon and Orbitz are among the companies urging Illinois lawmakers to legalize gay marriage.

“To be competitive, a state must create an equitable, fair and respectful environment for all of its citizens. For this reason – among others – it is vitally important that Illinois lawmakers enact marriage equality soon,” the business leaders say in an open letter to lawmakers.

“Marriage equality would strengthen the workforces of Illinois employers, who know there is no substitute for employees with diverse backgrounds and experiences. Companies must understand a changing marketplace and be able to connect with their customers; having a diverse workforce is a part of that. That's one reason many employers have adopted non-discrimination policies and offer domestic partner benefits.”

“Marriage equality promotes economic development, too. According to the UCLA School of Law's Williams Institute, allowing same-sex couples to marry would generate between $39 million and $72 million in revenues for Illinois businesses, creating $4.5 million to $8 million in new sales and lodging tax revenues over three years.”

Also signing onto the letter are the heads of Navistar International, Johnson Publishing and Morningstar Inc. Laura Ricketts, co-owner of the Chicago Cubs, and Fred Eychaner, chairman of the Newsweb Corp., also signed. Ricketts and Eychaner are both openly gay.

(Related: Greg Harris: Illinois on “fast track” to legalize gay marriage.)