LAWRENCE, Kan. -- The state's first domestic partnership registry goes into effect Wednesday, allowing same-sex couples living in this city to register in a state where voters rewrote the constitution two years ago to ban gay marriages.

City Clerk Frank Reeb said the registry, which also is open to unmarried heterosexual couples, doesn't mean those signing up will enjoy any new legal rights. He said 40 to 50 couples are expected to register either in person or online.

Both gay and straight couples are eligible to register. Couples must be Lawrence residents, 18 years or older, and share the same home.

"On the online registry, we ask them to acknowledge that this creates no legal rights for them other than they will be in the city registry as domestic partners," Reeb said.

Lori Messinger, a board member of the Lawrence-Douglas County chapter of the Kansas Equality Coalition, said the registry will make it easier for domestic partners to qualify for health insurance and other benefits from employers. More than half of the Fortune 500 companies extend some type of partners benefits.

Companies extending such benefits often accept registration as proof of an ongoing relationship and require more detailed documentation without it.

"It shows a sign of ongoing commitment that insurance companies will accept," Messinger said.