(CNN) — Maryland became the eighth U.S. state to allow same-sex marriage Thursday as Gov. Martin O’Malley signed legislation he said secures the “human dignity” of all residents, including gay and lesbian couples.

A standing-room crowd in the Maryland State House cheered O’Malley as he emerged from his office to sign the legislation, flanked by state Senate President Mike Miller and House Speaker Michael Busch.

“The way forward is always found through greater respect for the equal rights of all,” the governor said.

Six states and the District of Columbia already issue same-sex marriage licenses — Connecticut, Iowa, Massachusetts, New Hampshire, New York and Vermont. Five states — Delaware, Hawaii, Illinois, New Jersey and Rhode Island — allow civil unions that provide rights similar to marriage.

The Maryland House of Delegates approved the measure O’Malley signed Thursday less than two weeks after Washington state legislators voted to legalize same-sex marriage. That measure will take effect in the summer if it survives a likely court challenge.

The country is slowly moving forward.