The U.S. dollar saw inflation at an average rate of 2.88% per year between 1900 and 2016. $0.21 in the year 1900 is worth $5.65 in 2016.
The inflation rate in 2016 was 0.74%.
Source: The Bureau of Labor Statistic's annual Consumer Price Index (CPI), established in 1913. Inflation data from 1665 to 1912 is sourced from a historical study conducted by political science professor Robert Sahr at Oregon State University.