The Meyerhoff and Griswold families have jointly pledged $1 million to the Maryland Historical Society to help it complete a four-year capital campaign, society officials said.
The gift -- each family is contributing $500,000 -- would be one of the largest ever given to the Mount Vernon institution. It marks the first time the two prominent families have joined forces in philanthropy.
The pledge comes in the form of a "challenge" requiring the society to complete its fund raising by year's end. The campaign has raised $26 million, including the joint gift, and seeks another $3 million.
The two families' contribution would fund construction of a building linking the former Greyhound Bus station on Centre Street, acquired from the city, and the main society building on Monument Street.
"The Meyerhoff family and my family have been close for years, and we're both supporters of the historical society," said Jay S. Griswold, 58, chairman emeritus. "This is our first [joint] philanthropic venture, which grows out of a long commercial relationship."
Griswold said his Irish ancestor, Alexander Brown, founded the Baltimore investment house of the same name. That firm helped take the Meyerhoff family company public in 1970.
Harvey M. "Bud" Meyerhoff, 74, a society trustee for three years, took up Griswold's idea of a partnership.
"I think the historical society has become a much improved place," Meyerhoff said. "It now has outreach programs and broad-based exhibits that truly tell the story of Maryland to the broadest segments of our society. It's a much more inclusive and encompassing organization and program now than 25 years ago. When Jay became chairman, that change took place."
The society, founded in 1844, has one of the nation's largest collections of Americana, executive director Dennis Fiori said, encompassing manuscripts, furniture, paintings, quilts and other items. Next month, an exhibit of its storytelling Baltimore Album quilts will be displayed after returning from a museum tour in Japan.
Fiori described the joint gift as "serendipitous." He added, "The pieces came together, and we said, 'Hey, let's make it a challenge to stimulate other gifts.'"