American couples are readying themselves for a midnight celebration at the State House in Concord, New Hampshire where gay marriage will become legal as 2010 begins.

New Hampshire is the fifth state in the Union to legalise gay marriage, joining Iowa, Massachusetts, Connecticut and Vermont, with Washington DC broadly expected to follow later in the year.

While gays in the state have had the right to civil unions for two years, the legislation eliminates differences between gay and straight unions.

Current unions between gays and lesbians will be legally converted to marriages automatically over the coming year, but many are choosing to reaffirm their commitments and mark the implementation of the law, alongside couples who have waited for the legalisation of marriage before cementing their relationships.

New Hampshire residents, retired reverend Eleanour McLaughlin, 74, and Elizabeth Hess are one such couple. Devout Episcopalians, they have held out for gay marriage and incorporated their church into the ceremony. McLaughlin and Hess originally marked their commitment to one another in 1991 in an unofficial ceremony, holding out for equality in marriage before marking the relationship officially.

They have been together for 19 years. Hess, 62, said: “We want people to recognize we had to wait a long, long time.”