[2] The bill was reported to the full Senate by Connecticut's George P. McLean on January 25 with an amendment reducing the authorized mintage from 500,000 to 250,000 and a recommendation that it pass.

The bill was passed by the House without recorded objection,[7] and was enacted into law with the signature of the new president, Warren G. Harding, on his inauguration day, March 4, 1921.

[2][8] While the legislation was still pending in Congress, on January 29, 1921, Senator Spencer wrote to Charles Moore, chairman of the Commission of Fine Arts (CFA), regarding the bill.

Moore replied on February 2, advising that one of the few American sculptors capable of designing a coin be hired, and that the resulting work be subjected to the friendly criticism of other artists.

[9] The hired sculptor could choose among these concepts, Moore suggested, and decide which could be used to best effect, with Montgomery's approval and that of the Fine Arts Commission.

"[10] Montgomery also proposed that a star with the number "24" (Missouri being the 24th state) be included in the design, but be removed from the die after 5,000 coins were struck.

[11] The Fine Arts Commission hired Robert Ingersoll Aitken, a sculptor best known in numismatic circles for his design for the $50 Panama Pacific gold pieces.

[12] To speed production, the Medallic Art Company produced hubs from Aitken's plaster models, from which working dies to strike the coins could be made.

[14] The bust of frontiersman Daniel Boone, who lived in Missouri for the final quarter century of his life, appears on the obverse.

[15] Anthony Swiatek and Walter Breen, in their 1988 book on commemorative coins, note speculation that the obverse may have been inspired by Albin Polasek's sculptured bust of Boone in the Hall of Fame for Great Americans in New York City.

[16] The 1921 Report of the Director of the Mint describes the interaction as "Daniel Boone, with powder and rifle, directing the attention of an Indian to the westward course of the white man".

[18] The design was liked at the time of issue; several specimens were shown and admired at the 1921 American Numismatic Association convention at Boston in August, soon after the coin's release.

[20] He suggested that the figures on the reverse stand "like Roman soldiers in an Antonine relief on the Arch of Constantine or Renaissance condottieri in a large fresco of court ceremonials.

[21] A total of 50,028 Missouri Centennial half dollars was struck at the Philadelphia Mint in July 1921, 28 being reserved for inspection and testing at the 1922 meeting of the annual Assay Commission.

The Sedalia Trust Company distributed the coins at a price of $1 on behalf of the centennial commission, selling both varieties by mail and the plain ones at the exposition in August.