DENVER - Civil unions for gay couples has been signed into law in Colorado in a dramatic turnaround for the state, where voters banned same-sex marriage in 2006 and restricted protections for gays 21 years ago.

Democratic Gov. John Hickenlooper signed the bill as dozens of gay couples looked on and cheered during a ceremony Thursday near the state Capitol.

The law takes effect May 1.

Colorado joins eight states that have civil unions or similar laws. Nine states and the District of Columbia allow gay marriage.

The passage in Colorado is particularly remarkable because of its gay-marriage ban, and because voters approved a ban on municipal antidiscrimination laws to protect gays in 1992.

Some branded Colorado a "hate state" at the time, and the U.S. Supreme Court found the law unconstitutional four years later.