Historian Carl Sferrazza Anthony’s new book, Florence Harding: The First Lady, the Jazz Age, and the Death of America’s Most Scandalous President (William Morrow), began more than 20 years ago, when the author was a freshman at George Washington University. While taking an American history course, Anthony bypassed the usual library research and called Alice Roosevelt Longworth, the longtime Washington socialite and daughter of Theodore Roosevelt. The elderly lady was happy to see him.

Longworth regaled Anthony with tales of the famous presidents she had known, especially the all-but-forgotten Warren Harding. “She gave me a lot of details and information—weird, errant facts and stories that didn’t fit in anywhere else,” Anthony says. “Over the next 20 years of research, a lot of little things she had said that I had written down with question marks became marvelous puzzle pieces that finally fit in place.”

In particular, Longworth put Anthony, now 38, on to Harding’s wife Florence (1860-1924), a prototype for Eleanor Roosevelt, Nancy Reagan, and Hillary Rodham Clinton. She was the first president’s wife to voice her political views publicly by holding press conferences. She championed equality for women. She was an animal-rights activist. She was a bit of a flapper, too: the first First Lady to ride in an airplane, the first to be a fan of jazz, the first to eat Eskimo Pies, the first to invite Hollywood stars into the White House. “The Hardings were more complicated than meets the eye,” Anthony says. “Maybe that’s why the book”—which checks in at nearly 700 pages—”is so damn long.”

Florence is Anthony’s fourth book. First he wrote a two-volume history of the first ladies, followed by an attempt—largely in vain—to present a well-rounded portrait of Jacqueline Kennedy Onassis.

Anthony’s newest book benefited greatly from both its early start and its much-delayed finish. When he began, Anthony was able to interview the last surviving people who knew the Hardings personally, including Longworth, who died in 1980, three years after she sat for his interview. More recently, Anthony got hold of Florence’s personal diary, which surfaced last year at an Ohio barn auction. It is the only place in which Florence “painfully and ragefully finds an outlet for dealing with her husband’s adultery,” Anthony says.

August 2 is the 75th anniversary of Warren Harding’s death at a San Francisco hotel. (Anthony will be lecturing there to commemorate the event.) Noting that Florence was a sucker for astrology, Anthony reports that “friends of mine who are astrally inclined are joshing to me that she’s manipulating [the timing] from the other side.” Though Anthony himself isn’t a fan of the occult, he admits that the timing of his book “really is strange.”

—Louis Jacobson