King George VI places a wreath on the Canadian Cross of Sacrifice at Arlington National Cemetery in Washington, June 9, 1939. The cross was erected by the Canadian Government in memory of United States Citizens who served and died in the Canadian Army during W.W.I. (Library and Archives Canada).
A full list of 600,000 members of the Canadian Expeditionary Forces can be researched for a fee on the Ancestry.com list Canada, Soldiers of the First World War, 1914-1918 . Entering “United States” or “USA” in keyword search will return approximately 50,000 records. The list is owned by Library and Archives Canada, but licensed to Ancestry.com.
Attestation papers of known named individuals, with family and other information, are available without cost on the Soldiers of the First World War Database of the Library and Archives Canada.