We use vintage 2021 population estimates for the number of infants and toddlers in the United States. The estimates are based on the 2020 Census; the Census Bureau adds births, subtracts deaths, and adds net migration to the enumerated resident population from the 2020 Census.
Source: U.S. Census Bureau, Population Division. (2021). Annual state resident population estimates for 6 race groups (5 race alone groups and two or more races) by age, sex, and Hispanic origin: April 1, 2020 to July 1, 2021. https://www.census.gov/data/datasets/time-series/demo/popest/2020s-state-detail.html