Upon the entry of the United States into World War I, the American Expeditionary Forces (AEF) were created by the War Department on short notice from existing units, filled up with men from the training camps and deployed with only their personal weapons and equipment. The US Army was not prepared for combat in France, and the remarkable achievement of the AEF's commanding officer, John J Pershing, was the creation of an American field army, built and nurtured from the bottom up. This book details the organizational structure, training and doctrine of the AEF and illustrates how it came to make a significant contribution to Allied victory in World War I.
A lot of "nuts and bolts" information on how the AEF units were setup in France - written in the customary Osprey format. Numerous tables showing manpower breakouts by what types of use for the men (almost exclusively men) the many units. A lot of emphasis on the administrative side of how those units were setup and run. To be sure there's some discussion of equipment and battles, but the emphasis is on the top level of operations.
I also have a "companion" book: "US Doughboys 1916-1918' which gets more into the individual soldier - his training, his gear, his life in the trenches and on the attack.
I recommend both Osprey books (I used both as very helpful reference works while I read other WW1 Histories)