While the standard U.S. Army infantry rifle at the start of World War I was the most excellent M1903 Springfield, most soldiers would end up with an Enfield.
Kevin with IV8888 covers the story of his Remington M1917, an Enfield design converted from the .303 caliber P14 Pattern rifle which was made in the U.S. for the King’s soldiers during the first part of the war. With Winchester and Remington already making the Enfield here in the states when America entered the Great War against the Kaiser, conversion to 30.06 ended up with a great bolt-action rifle of which nearly 2.2 million were produced in short order to help arm Uncle Sam’s rapidly expanding Army.
Officially, the “U.S. Rifle, Model of 1917, Caliber .30” it is more commonly just called the 1917 Enfield or American Enfield, and Remington even kept the rifle in standard production as the Model 30, marketed as a deer gun, until 1940.
And you can see why in the above video.