In April 1917, when war was declared, the US Army consisted of only 108,000 Regular Army and 122,000 (part-time) National Guard forces.

Enlistment and training began immediately at Army camps all across the US. A small number of advance officers and support staff arrived in France in June 1917 to assess the war situation.

By March 1918 there were 250,000 semi-trained U.S. soldiers in France, which increased to two million men on French soil, in arms, by the end of the war in November 1918. Overall 4.4 million men had been called up by November 1918.

The American Expeditionary Forces of World War One were made up of:

• The Regular Army: 1st - 20th Divisions
• The National Guard: 26th- 42nd Divisions
• The National Army: 76th- 97th Divisions

From a Kansas/Missouri perspective 3 Divisions contained the majority of the draftees and volunteers from the two adjoining states:

• 35th (Santa Fe)
• 42nd (Rainbow)
• 89th (Middle West)

• 3rd Division, Regular Army Summary
• 35th (Sante Fe) Division Summary
• 89th (Midwest) Division Summary

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