and it was based on talk of his times. especially post wwII. it could have been used by feds if certain desirable land was privately held. eminent domain for defense, unless ED was used for the common good anyway.
I heard that ike was inspired by autobahn. in angeline's link they mention the downside. the highways work equally well (good or bad) when the tide of war turns.
the effect on commercial transport of goods was enormous. trucking replaced 'king' rail. flexibility and cost were key element. the exceptions were large quantities of chemicals, coal,grains. etc. it also was a major factor in creating the suburbs. and the one thing we all hate; longest parking lots in the world.