While Carter's election - by an unusual unanimous vote - marks a significant milestone, the past dies hard.
One traditional toast began, "Gentlemen, charge your glasses!" even though half the celebrators were women.
Carter, 67, and her husband, John Aglialoro (also a member), cofounded UM Holdings Ltd. in 1973. The private-equity investment firm has owned more than 40 businesses, from renal dialysis companies to a small airline. Carter is president of UM, vice chairman of CYBEX board of directors, a board member of the Penn Mutual Life Insurance Co., and a former chairman of the board of directors of the Federal Reserve Bank of Philadelphia.
In introductory remarks, Carter's friend and fellow league member, New Jersey State Sen. Diane Allen, recalled that the club was once not so enthusiastic to have women in its midst.
"Some places were still off-limits," Allen recalled, including the billiard room and the card room. "Joan, with her great business sense, realized that if we can't use the whole league, we shouldn't pay the whole price."
Carter drafted a letter, which the other women signed, suggesting their dues should be prorated.
The tactic worked, and equal access was granted.
One member after another Tuesday hailed Carter's election as a boon for the league.
"The celebration is about Joan Carter," said Ed Turzanski, "not because she's a lady but because she's the best possible person for the job."
Turzanski, 51, said he had been a guest at the league for 15 years before joining in 2004. A senior fellow at the Foreign Policy Research Institute, a professor of political history at La Salle University, and a member of the CIA under President Ronald Reagan, Turzanski is contributing to a book about the history of the Union League, to be published in 2012 on the club's 150th anniversary.
"I'm writing the final chapter, 1970 to the present. It's a period of firsts. The first African American member [in the early 1970s]. The first women, in 1986. The first Democratic president. The first Catholic president. And now the first female president."
The impetus to widen the league's reach is in part an attempt at self-preservation, since hard economic times have forced other city clubs to fold. There were once 226 Union Leagues in the country; now there are three.
According to the National Club Association, the average cost to join a club is $5,000 to $6,000, and dues average $2,500 per year. Philadelphia's league charges a $3,600 initiation fee and $4,000 annual dues.
"A lot of the private clubs around the country had restrictive admission policies until the 1980s," said Susanne Wegrzyn, president of the National Club Association, in Washington. "As the culture was changing, the clubs began to change as well."
Local governments pressured clubs to diversify, by threatening to remove their tax-exempt status.
Today, said Wegrzyn, among the organization's clubs, 20 percent of members and 6 percent of presidents are women.
Carter grew up in Pittsburgh, the only child of a schoolteacher and a businessman. After graduating from the College of Wooster in 1965 with a music degree, she taught high school German and nursery school, until she met her husband and began building their company.
Carter's 24-year rise to the presidency is about average, said James Straw, a member since 1979 and league president from 1999 to 2000.
"In terms of process and evolution, there are those who wanted to speed up the process and others throwing the anchor off the transom of the boat."
In her remarks, Carter said that although being in such a small minority was awkward at first, she had never felt unwelcome.
"The league has absolutely enriched my life," she said. At receptions honoring recipients of the league's highest awards, she said, she has met Supreme Court Justices Antonin Scalia and Clarence Thomas, Gen. David Petraeus and Laura Bush. If she had never joined the league, she said, "I wouldn't have heard them in a million years."
For the ceremony, Carter wore a platinum and pearl Mikimoto brooch she had bought in Japan years ago for her mother. "I think of her," she said, "whenever I wear it."
Carter said she plans to expand the club's membership beyond the current 3,200, gradually eliminate outside catering, and usher in a historical center next spring that will allow the public to view the club's formidable collection of Civil War documents.
Joining in the applause, Frederick Haab, chairman of the nominating committee, said, "It's historic."
Haab, chairman of F.C. Haab Co., an oil and heating firm, said he wondered how his father, a member of the league's old guard, might view this change.
"I don't know what he'd think," Haab said. "But I think it's terrific."
Contact staff writer Melissa Dribben at 215-854-2590 or email@example.com.