Mo. Rev. Stat. § 41.170
The adjutant general shall compile and maintain from the original muster rolls in his office and such additional sources as he can command, a complete alphabetical list of those persons who served in the wars of the United States, who at time of entry into service were residents of the state or territory of Missouri, and including the War of 1812, the Mexican War, the Indian Wars, the war between the states, the Spanish-American War, the Philippine War, Mexican Border Service, World War I, World War II, and any subsequent war, and shall include therein the military history of each person as complete as can be obtained. In his office shall likewise be kept the colors, standards and battle flags of the troops. He shall furnish a certificate of war service, on request, without charge to any veteran or lineal descendant of a veteran.
§ 41.170, RSMo