The 100th anniversary of the admission of Missouri to the Union was celebrated in Sedalia during August 1921. To mark the occasion, Congress authorized the coinage of a fifty-cent piece. Robert Aitken designed the coin, which shows the bust of a frontiersman on the obverse, and a frontiersman and Indian on the reverse. The first coins struck show 2*4 incused, indicating that Missouri was the 24th star in the flag. The type without this marking was struck later, but was the first to be sold.