PORTLAND, Maine — The city and its surrounding communities are one of the least diverse metro areas in the nation, according to a study last fall by Brown University researchers.

The Portland-South Portland-Biddeford area ranked No. 11 on the list of the least diverse areas. Bangor ranked No. 5; Lewiston-Auburn was No. 25.

But don’t tell that to Susie Bock.

Bock is director of the Jean Byers Sampson Center for Diversity in Maine. The center, at the University of Southern Maine library on Forest Avenue, is a treasure trove of books, magazines, photographs, posters and artifacts relating to the state’s African-American, Jewish and lesbian, gay, bisexual and transgender communities.

“Although it may not seem to be, Maine is a diverse place, and it’s becoming even more so,” Bock said. The role of the center is to “celebrate that diversity, and the fact that we’re not all the same.”

The center is launching a $100,000 fundraising campaign with a concert by pop singer Kim Kuzma at 7 p.m. Thursday at One Longfellow Square.

Each semester, the center provides materials and learning exercises for dozens of USM classes. Although little known outside the university, the center and its more than 1,000 linear feet of holdings is also open to the public. There are plenty of books, but many unusual items too.

They include “WHITE” and “COLORED” signs for segregated public bathrooms, newsletters for a Jewish student group and an advertisement for a local theater’s production of a gay musical farce, “Oklahomo!”

“This is a hands-on place,” Bock said. “If people don’t have a chance to touch material from another culture and another time, how are they going to value their own?”

Despite the Brown University findings, issues of diversity have long played out in the state.

Portland’s Abyssinian Meeting House, at 75 Newbury St., was a stop on the Underground Railroad during the Civil War era, helping bring escaped slaves to freedom. In the late 1800s, Portland was a haven for such a large influx of Jewish immigrants that the city became known in New England as “Jerusalem of the North.” And more recently, Maine made national headlines when same-sex marriages became legal on Dec. 29, 2012.

The center was founded in 1994, and is named after Jean Byers Sampson, a civil rights leader in Maine during the 1950s and 1960s who served as president of the NAACP’s Central Maine branch. The initial collection of books, papers and artifacts was donated by another local civil rights leader, the first president of the NAACP’s Portland branch, Gerald Talbot.

Museums and libraries devoted to individual cultures aren’t unusual. But the Sampson Center’s three collections, devoted to African-American, Jewish and LGBT history, represent an unusual combination. Bock said she’s not aware of any similar trio.

“What’s neat about the collections is that you wouldn’t think there would be ties among these communities, but there are,” she said. “Often one group that does not have power finds an ally in another.”

And regardless of how diverse Maine may be, the center plays a vital role, Bock added.

“Young people, all people, need to understand there are people who are different, and that they should be loved for who they are,” she said. “We need places like the Sampson Center so we remember this.”