From [www.abmc.gov] :

Please be advised that we only have the records of those casualties that are buried in our cemeteries or are placed on the Walls of the Missing a total of 33,717 records. There were 118,518 American casalties in World War I.

…which answers a question that was in the back of my/our heads when touring Tyne Cot and Arras cemetaries; contrast is given by the content of a plaque that I found in Reims cathedral, comemorating the over one million soldiers of the British Empire who fell in “The Great War”.

The French, German, and other figures elude me.