Ed Desser, a sports television consultant and former N.B.A. executive, described several factors leading to a "perfect storm" of viewership on Sunday night: a time of year with light sports competition, a strong American team to root for, a rematch of the 2011 Women's World Cup finalists, and weeks of buildup for the American team on both Fox and Fox Sports 1.
"This was an event, the sort of thing that galvanizes an audience," Desser said.
With the World Cup being played in Canada, Fox also had the advantage of North American time zones and prime-time slots for the games played by the United States team.
The audience for the women's final exceeded those for the recent N.B.A. finals and for last year's World Series. In fairness, though, World Cups and Olympics come along every four years and are not directly comparable to annual best-of-seven series.
Read MoreFor US soccer wages, women still fall far short of men
Still, it has to come as something of a surprise that Game 7 of the compelling World Series between the Kansas City Royals and the San Francisco Giants in October attracted 23.5 million on English-language television, or two million fewer than the American women drew on Sunday night. The sixth and deciding game of the N.B.A. finals, won by Golden State over Cleveland and featuring Stephen Curry and LeBron James, also lost out to the women by about two million viewers.
The men's final of the 2015 N.C.A.A. men's basketball tournament, in contrast, topped the women's final with 28.3 million viewers. But it is the women who are surging.
A blowout like Sunday's World Cup final often prompts viewers to tune out. But that did not occur this time. The American team scored four early goals and entered halftime in Vancouver with a 4-1 lead, which is close to insurmountable in soccer. Still, an estimated audience of 18.2 million viewers at the start of the match, at 7 p.m. Eastern, grew to a peak of 30.9 million viewers late in the game, between 8:30 and 8:45 p.m.
Fans might have stayed until the end to see if Carli Lloyd would score a fourth goal. Or they might have been waiting for Abby Wambach to enter the game for what seems virtually certain to be her World Cup farewell. Or perhaps they simply wanted to see the United States team celebrate the country's first World Cup in 16 years in front of a buoyant capacity crowd of American fans in Vancouver.