One writer in the email list exchange supplied by the commenter (below) brings up the interesting point that considering the "first" women's shelter as being part of the second wave of feminism/women's liberation overlooks the broader history of solidarity and aid among women. So that's something to weigh.

But returning to the United States in the 1970s, Susan Brownmiller's In Our Time: Memoir of a Revolution has a chapter on the battered women's movement. After acknowledging that "rudimentary shelters were popping up in activists' homes across the country," she goes on to describe this event from 1970:

"...Sandy Ramos believes she started the first shelter [later named Save Our Sisters] in North America, almost by accident, in her purple-painted, three-bedroom house at 133 Cedar Avenue in Hackensack, New Jersey...'I didn't know what I was doing,' she says, 'but I knew I wanted to share my house with other single mothers.'"
(p.262 in the 1999 edition published by the Dial Press)

You may also want to consult what Brownmiller refers to as the "first American book on domestic violence," Battered Wives by Del Martin (1976), as well as Women and Male Violence: The Visions and Struggles of the Battered Women's Movement by Susan Schechter (1982). "[Schechter's] first four chapters are a more or less chronological overview of the movement's creation, flowing from specific examples to more general discussion and analysis of the establishment of the first shelters and the problems, theories, and strategies which began to emerge as the movement grew," according to a review by Tricia Lootens in the 9/30/83 issue of off our backs.