By 1896 swimming had become well established and was one of the sports in the first modern Olympic Games, held in Athens, Greece. At the 1904 Olympics in St. Louis, Missouri, American swimmer Charles Daniels won two gold medals, signaling the beginning of a long period of American success in international competition.
Women's swimming was introduced to the Olympic program in 1912 in Stockholm, Sweden. That same year American men's swimmer Duke Kahanamoku won the 100-meter freestyle race, a title he repeated in 1920 (the next time that distance was contested), and George Hodgson of Canada won the 400-meter and 1500-meter freestyle races. Johnny Weissmuller, one of the best known American swimmers, won a total of five gold medals at the 1924 and 1928 Olympics. In 1926 American Gertrude Ederle, who had won a gold medal in the 1924 Olympics in the 400-meter freestyle relay, became the first woman to swim across the English Channel. (In 1875 Matthew Webb of England had been the first man to do so.)
In the 1930s Japanese swimmers challenged American dominance in the men's events, but American women continued to be successful in international women's swimming. Buster Crabbe was one of the most famous male swimmers of the period, while leading female swimmers included Eleanor Holm and Helene Madison of the United States and Hendrika Mastenbroek of the Netherlands. In the 1950s and 1960s Australian swimmers enjoyed great Olympic success, including Murray Rose, David Thiele, and Dawn Fraser. At the 1972 Olympics in Munich, West Germany, American Mark Spitz became the first swimmer to win seven gold medals at one Olympics. American swimmers dominated the men's events at the 1976 Olympics in Montréal, Québec, Canada, but swimmers from East Germany won almost all the gold medals in the women's competition. American Shirley Babashoff, however, won a total of eight Olympic medals (two gold and six silver) in 1972 and 1976. The 1980 and 1984 Olympics, held in Moscow and Los Angeles respectively, were affected by large boycotts by many countries. Many athletes did not compete. In 1988 East German Kristin Otto won six gold medals at the Olympics in Seoul, South Korea. The most successful American swimmers of the 1980s and 1990s include Matt Biondi, Janet Evans, Tom Jager, Summer Sanders, Mike Barrowman, and Pablo Morales.