In 1951, Klopfer was awarded the gold medal at the U.S. Championships. Having won at age 15, she was the youngest U.S. senior ladies' champion until Tara Lipinski won in 1997 at age 14. Klopfer obtained the bronze medal in Milan at the 1951 World Championships, standing on the podium with Jeannette Altwegg and Jacqueline du Bief.