In https://en.wikipedia.org/wiki/Vaccination_schedule#United_St... it says 4 doses.
Also in your second link, in page 8 says
> All children should receive four doses of IPV at ages 2, 4, 6 to 18 months, and 4 to 6 years.
Also in your second link, in page 8 says
> All children should receive four doses of IPV at ages 2, 4, 6 to 18 months, and 4 to 6 years.
[0] https://www.cdc.gov/vaccines/vpd/polio/hcp/composition-dosag... [1] https://www.fda.gov/media/75695/download