Thousands of couples around the country are applying for marriage licenses today, with the expectation that they will be denied, to mark the 12th annual Freedom to Marry Week.
Hundreds are expected at City Hall in Lower Manhattan.
Protests are planned in cities and communities across the country.
Some of the largest gatherings are expected in California, where voters approved Proposition 8 last November – banning same-sex marriage.
Massachusetts and Connecticut are the only states that allow gay marriage.