How common was polio in the United States?
Polio was one of the most dreaded childhood diseases of the 20th Century in the United States. There were usually about 13,000 to 20,000 cases of paralytic polio reported each year in the US before the introduction of Salk polio vaccine in 1955. Polio peaked in 1952 when there were more than 21,000 reported cases. The number of cases of polio decreased dramatically following introduction of the vaccine and the development of a national vaccination program. In 1965, only 61 cases of paralytic polio were reported compared to 2,525 cases reported cases just five years earlier in 1960.
