Nonpartisan officials largely comprise the group from Plano, Geneva, North Aurora, St. Charles, Elburn, Yorkville and Sleepy Hollow.
They released a letter Tuesday morning through the gay marriage advocacy group Illinois Unites for Marriage. The mayors say same-sex couples and their families are denied full protection under Illinois law.
Same-sex marriage legislation got a February Senate OK but has not been called for a vote in the Democratic-controlled House.
Illinois allowed civil unions in 2011. There are now 14 states, plus Washington D.C., that allow same-sex marriage.
In an earlier version of this story, The Associated Press, relying on information from an advocacy group, erroneously reported a list of seven suburban Chicago mayors who signed a letter in support of same-sex marriage legislation. The final list included the mayor of Yorkville, not DeKalb.
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