In 1900, the average American could expect to live 47.3 years. Diphtheria, measles, and whooping cough killed thousands each year, and most victims were children. By the 1960s, vaccinations had those contagious diseases under control. In fact, child-mortality rates have decreased about 60 percent since 1960 among children ages 1 to 9, and 43 percent among children ages 10 to 14. Americans now live an average of 75.8 years, and injuries are the most common cause of childhood death.