Hallmark has joined California and Massachusetts in recognising gay partnerships.

The popular greeting card company has been rolling out same-sex wedding cards featuring two tuxedos, overlapping hearts or intertwined flowers, with best wishes inside.

“Two hearts. One promise,” one says.

The language inside the cards is neutral, with no mention of wedding or marriage, making them also suitable for a commitment ceremony.

Hallmark says the move is a response to consumer demand, not any political pressure.

“It’s our goal to be as relevant as possible to as many people as we can,” Hallmark spokeswoman Sarah Gronberg Kolell said.

Hallmark started offering “coming out” cards last year, and the four designs of same-sex marriage cards are being gradually released this summer and will be widely available by next year.

No sales figures were available yet.

“When I have shopped for situations like babies or weddings for gay friends I have good luck in quirky stores,” said Kathryn Hamm, president of the Web site GayWeddings.com.

The Williams Institute at the UCLA School of Law estimates that more than 85,000 same-sex couples in the United States have entered into a legal relationship since 1997, when Hawaii started offering some legal benefits to same-sex partners.

It estimates nearly 120,000 more couples will marry in California during the next three years, and that means millions of potential dollars for all sorts of wedding-industry businesses.