The interstate highway system was not built for commercial trucking.
> In the Federal-Aid Highway Act of 1938, Congress asked the
BPR for a report on "the feasibility of building, and cost
of, superhighways... including the feasibility of a toll
system on such roads." The BPR based its report on data
collected from extensive highway planning surveys that had
been conducted around the country beginning in 1935. The
origin-and-destination surveys showed that transcontinental
traffic was limited, with traffic heaviest around cities and
in interregional movements. Given the low income of most
motorists, toll roads would have a traffic-repelling
character. As a result, most routes would not carry enough
traffic to generate sufficient revenue to pay off bonds
needed to finance their construction.
Instead, the BPR recommended construction of a network of
toll-free express highways. The BPR's description of "A
Master Plan for Free Highway Development" was its first
description of what would become the Interstate System. Based
on the survey data, the BPR explained that the primary
justification for the network was passenger traffic,
particularly congested city traffic, not interstate trucking.
In fact, the report made little reference to trucks. [0]
Commercial trucking would not start to take foothold over rail until the 1960s, primarily under President Johnson.
And also built to allow rapid evacuation of large cities in case of nuclear attack. I think it's lost on a lot of people today just how many things we did in the 50s, 60s, and 70s because we were scared of being bombed.
> In the Federal-Aid Highway Act of 1938, Congress asked the BPR for a report on "the feasibility of building, and cost of, superhighways... including the feasibility of a toll system on such roads." The BPR based its report on data collected from extensive highway planning surveys that had been conducted around the country beginning in 1935. The origin-and-destination surveys showed that transcontinental traffic was limited, with traffic heaviest around cities and in interregional movements. Given the low income of most motorists, toll roads would have a traffic-repelling character. As a result, most routes would not carry enough traffic to generate sufficient revenue to pay off bonds needed to finance their construction.
Instead, the BPR recommended construction of a network of toll-free express highways. The BPR's description of "A Master Plan for Free Highway Development" was its first description of what would become the Interstate System. Based on the survey data, the BPR explained that the primary justification for the network was passenger traffic, particularly congested city traffic, not interstate trucking. In fact, the report made little reference to trucks. [0]
Commercial trucking would not start to take foothold over rail until the 1960s, primarily under President Johnson.
[0]: https://www.fhwa.dot.gov/interstate/freight.cfm