American World War II Tanks
America has some of the most technologically advanced tanks today, but America was slow to develop military tank and amored fighting vehicle technology when it was a new concept.
Obviously the USA was not directly involved in the first year or so of World War Two, so she had no pressing need to develop tanks at the start, which meant she was even further behind the British by the time America became fully involved in WWII.
However, like the USSR (Russia), America had a huge amount of resources and manpower to create vast numbers of fighting vehicles and tanks. In fact the USA was better placed than anyone as it already had a vast auto industry that was easily adapted to making tanks.
Of the most significant tanks of WWII, the American M4 Sherman Tank was up there with the Russian T-34 as one of the mainstays of the allied forces.
(Weights are in long tons and kilograms.)