A survey has revealed that thousands of same-sex couples in the US state of Illinois have married since the law changed earlier this year.

Illinois Governor Pat Quinn signed the state’s equal marriage bill into law in December, however, same-sex weddings were technically only set to take place from June 1, 2014 when the law took effect.

But despite the 1 June start date, a Chicago federal judge in February ruled that the state’s ban on same-sex couples marrying was unconstitutional, opening the door for some couples to marry immediately.

According to the Equality Illinois survey of all 102 counties, at least 3,274 marriage licences were issued to same-sex couples, and in addition, 1,694 civil unions were converted to marriage.

The group also announced that couples married out-of-state had their marriages recognised in the state.