The Senate's 12-9 vote sends the bill to Democratic governor Jack Markell, who supports the measure and planned to sign it later in the day. It would go into effect July 1.
"I think this is the right thing for Delaware," the governor said after the vote, while posing for pictures with supporters outside his legislative office. "It took an incredible team effort."
Unusually, Delaware is also converting all civil unions into marriages over the next year, rather than letting people vote with their feet. Though given that they only came into effect at the beginning of last year, and only 500 people have taken them up, that seems less of an intrusion than it would be if the system had been operating for years.
Next up: Illinois and Minnesota. Those are much tighter fights, but hopefully equality will win at least one of them...