Same-sex couples can now get married throughout Illinois - three months earlier than the state's ban on gay marriage was due to end.
'Nobody should have to wait for equal rights when it comes to love,' Governor Pat Quinn said in a statement.
Quinn's statement followed Attorney General Lisa Madigan's suggestion in a letter this week that county clerks across the state allow same-sex couples to wed.
Illinois' Religious Freedom and Marriage Fairness Act was not due to go into effect until 1 June.
But Madigan made her suggestion to forge ahead after a judge's recent class action lawsuit ruling that Cook County could immediately begin issuing licenses.
Since last Friday (28 February), more than 250 same-sex couples have been issued marriage licenses in Cook County.
'I encourage every county clerk in Illinois to quickly follow the attorney general’s guidance,' Quinn stated. 'Following this guidance, the Illinois Department of Public Health will now accept all marriage licenses issued by any county clerk in Illinois.'
Madigan wrote that 'the protections guaranteed by the Constitution must exist without regard to county lines.'
She also stated that if a couple were denied a license and sued before 1 June, the Attorney General's office would take the position that such a denial is unconstitutional.