You will find loads of information about the Show Me State's participation in WWI on the Missourians in the First World War website maintained by Scott K. Williams. For instance:
"During World War I, approximately 156,232 Missourians served in the Army as soldiers, in addition to 14,132 in the U.S. Navy and 3721 in the Marine Corps. About half of these men went overseas, while the rest remained in the United States at training locations. Missouri had 11,172 casualties (1,270 killed in action; 493 mortally wounded; 887 died of disease; 141 died of accidents/other causes; 6,945 wounded; and 495 missing, of whom 209 were later accounted for). 782 Missourians died in training camps in the United States.
Harvey C. Clark, Missouri Adjutant General stated, "Missouri was represented in practically every company, battalion, corps, or contingent of the American Army and contributed its full quota to the officers reserve corps, the navy, the regular army, the aviation service, the marine corps, the engineers, railroad troops, and sanitary units."
Missourians in the First World War