American tank production began with foreign tanks. This approach was the most correct during the war, as it saved the most precious resource: time. This way, by the end of WWI, the American army ended up with M1917 light tanks, reworked French Renault FTs, and heavy Mk.VIII International tanks, made in the likeness of British heavy tanks. The latter were built using American components, most importantly, Liberty L-12 engines.
The issue with medium tanks was never resolved. By the end of WWI, the Entente only had a Medium Mk.A Whippet in this category, an example hardly worth following. The Medium Mk.A didn't survive for long, and the Mk.B and Mk.C that replaced it were more similar to the heavy "rhombus" tanks.
As for the Americans, they placed their bets on John Walter Christie. In April of 1921, the M1919 Medium Tank entered trials. On one hand, it was a very progressive design with a very powerful 6-pdr (57 mm) gun and decent mobility for the time. In addition, it was the first successful convertible drive tank.
On the other hand, only the central bogey actually had a suspension. As a result, driving off-road was torture for the crew. There were also problems with Christie's engine. A request was made to rework the tank, especially the suspension. Christie interpreted the request in a peculiar way. He did rework the suspension, but the tank turned into an SPG. This forced the military to say goodbye to Christie, but as it turned out, not for long.
Harry Knox, the father of the T1 light tank series, took what would later become the Medium Tank Mk.I as a basis. This distant relative of the Medium Tank Mk.A Whippet had a front engine, but a rear transmission. As a result, the turret and fighting compartment were shifted to the back. Thanks to this layout, the vehicle was much shorter than the Medium Mk.D. At the same time, the weight was reduced.