100 mph and traffic entering on the left? that's crazy talk.
In 1918, at the end of WW I, The US Army sent a convoy from Washington DC to San Francisco, Mostly following US rte 30. Averaging about 6 miles an hour, or 58 miles a day, it took 62 days for the 3,251 miles.
With depression dragging on and the specter of war on the horizon, this highway would enable moving our army quickly, plus jump start the depression economy. Even with all the New Deal CCC projects going on this was politically impossible.
During WW II the military, including Ike, were impressed with Germany's highway system, which Hitler had built to enable moving his army quickly plus jump start their sagging economy, in 1933. So Ike's Interstate Highway plan had to be inclusive to get the support in Congress, and with limited grades and minimum 16 ft clearances for missile carriers to please the military.