Organizers said they checked in 37 couples for an outdoor ceremony on the plaza of the Statehouse -- the building where the law was adopted and signed in 2007. Participants bundled up against below-freezing temperatures.
The civil-unions law -- enacted by the Democrat-dominated Legislature early last year and signed by Democratic Gov. John Lynch in May -- gives same-sex couples the rights, responsibilities and obligations of marriage without calling the union a marriage.
"We are a citizen legislature, and we legislated this into being," said state Rep. Gail Morrison, a Democrat and co-organizer of the event. She entered into a civil union with her longtime partner.