The New York Democrat wrote last week to the head of the National Register of Historic Places and National Historic Landmarks Program, supporting the theater's application for inclusion on the national register.
"The Cherry Grove site contributes to a greater understanding of civil rights movements as an evolutionary process towards change and represents a rare and exceptionally significant chapter in the struggle for gay and lesbian civil rights in the United States," she wrote.
The Community House and Theater "provided the first setting for a collective gay identity to openly appear in our nation's history," she said.
Diane Romano, president of the Cherry Grove Community Association, said the community house -- built in 1945 in Sayville and floated on a barge across the Great South Bay -- has been approved to be added to the state register. The theater, built as an addition in 1948, still hosts plays and cultural events.
"To have someone like Sen. Gillibrand to go out of her way to call for a national designation for Cherry Grove is simply one more step in moving the lesbian and gay community into mainstream America," said Romano, whose group filed the application for historic status. "It's very, very exciting, and to have recognition for all of the wonderful work that we've done for the arts is just great."
Romano said she anticipates a decision this summer on the national register application. The group has raised about half of the $600,000 it is seeking in a multiyear campaign to restore and renovate the community house.