That was definitely not true in the 1950s when I was a small boy in Calhoun County. My parents worried about my sister and me every summer, especially when we started wanting to go swimming. Many pools closed in August for fear of polio spreading.
In the 1950s, almost everyone knew someone who had had polio. A girl in my class had braces on both legs, and walked with crutches from her bout with polio.
In 1952, there were 58,000 confirmed cases of polio in the United States. In 1953, there were 35,000 confirmed cases. In 1954, Dr. Jonas Salk did massive field trials of his polio vaccine. In 1955, a nationwide vaccination program was started. By 1957, there were only 5,600 confirmed cases of polio in the United States. In 1958 and 1959, the Sabin oral vaccine was developed. I remember well one Sunday afternoon waiting in line at Alexandria School to take the two sugar cubes containing the Sabin vaccine. In 1962, the Sabin oral vaccine totally replaced the Salk vaccine. In 1964, there were only 121 cases of polio in the United States. This is a great success story about wiping out a disease that for many years was the scourge of young people as well as adults.
Note that one of the vaccines that children are still required to get before starting school is the polio vaccine.
League City, Texas