Although Hiram Maxim, the inventor of the machine gun, invented it in the United Kingdom, he was American by birth. During World War I America made a few of the most iconic machine guns in history, one of which was used all the way up until the end of World War II. America, didn't however use only machine guns made in America. We used many from all over including, but not limited to, France, Britain, and Belgium.
COLT-BROWNING M1895 - Known among troops as the "potato digger", this machine gun came in a few different calibers, such a .303 British and 30-06 Springfield. It fired about 600 rounds per minute, which was relatively quick for the time. Not many infantry variations were used since newer models had surfaced by the time the war came about. It was, however, used quite often as an aircraft machine gun.
BROWNING M1917 - Unlike the M1895, the Browning M1917 was water cooled, meaning it could fire for longer periods of time without having to replace barrels or let them cool down. It did have a slower, and more irregular rate of fire than the M1895, but it was much more reliable. It did not malfunction as often, and the water cooled barrel proved to be very effective in the battlefield.
BROWNING AUTOMATIC RIFLE - The Browning Automatic Rifle or BAR is one of the most Iconic rifles ever built. Though its use was made popular during World War II, it was indeed developed towards the end of the first world war. The BAR fired at about 600 rounds per minute and had a 20 round magazine. It was one of the first machine guns used effectively as an infantry weapon. It was, however, heavy, and limited to a 20 round magazine that went quick. It was also chambered in the 30-06 Springfield caliber, meaning carrying ammo was a chore. The BAR is arguably the first assault rifle ever produced.