Following world war 1 the united states experience a period of technological advancement in transportation which advancement in transportation occurred during this period

One of the highlights of World War I was the creation of the tank - initially called "land ships" - which emerged after the car boom a few years earlier and became a powerful way of combating the absurd trench wars in which machine guns already wreaked havoc.

We also find a predecessor to modern drones: the first unmanned aircraft to intervene in World War I was developed by the U.S. Navy !

the second significant cause of the great migration was the desire of black southerners to escape segregation, known euphemistically as jim crow. rural african american southerners believed that segregation - and racism and prejudice against blacks - was significantly less intense in the north.