A gay marriage law officially takes effect on Sunday in Illinois.

But unlike other states where pent-up demand from eager gay couples helped break marriage records, Illinois' rollout isn't expected to break many records.

That's because gay couples have been marrying in the state's largest county, Cook County, since February.

Cook County Clerk David Orr began issuing marriage licenses to gay couples on February 21 after a federal judge ruled that there was no need to wait for the marriage law to take effect. The ruling was limited to Cook County but 15 other counties followed suit.

“I've issued about 1,600 marriage licenses to same-sex couples since Feb. 21,” Orr tweeted on Thursday.

Only a handful of the state's remaining 86 counties are planning to open Sunday to help inaugurate the law.

Montgomery County Clerk Sandy Leitheiser was among those planning to process marriage-license applications on the law's first day.

“I'm here to uphold the law of Illinois, and if there's a way to accommodate couples based on need and special circumstances, I'm available,” she told the AP.

Illinois previously recognized gay couples with civil unions. Starting Monday, couples can convert their civil unions to marriages.