Some
people believe that U.S. Route 40 obtained its numerical
designation because it approximated the 40th parallel
lattitude line. This is incorrect. Route 40's proximity
to the 40th parallel is merely coincidence.
When the U.S. numbered highway system
was established in the 1920's, an orderly numbering
convention was sought. The group came up with this plan:
- Highway numbering would increase
southerly and westerly.
- East-west transcontinental highways
would be numbered in multiples of ten.
- North-south transcontinental highways
would be numbered ending in five.
- Three digit numbered highways would
be spurs off a two digit numbered highway -- and the
tens and unit digits would be the same as the highway
from which they spurred.
- Exceptions include:
- Route 1 (north-south along the
east coast)
- Route 2 (east-west along the
northern frontier with Canada)
- Route 101(north-south along the
west coast)
Believe it or not, there's an entire web
page devoted to the rationale of route numbering. Check
it out.
If east-west transcontinental highways
obtained their designation based on their lattitude,
all of our east-west highways would be numbered 30-48.
To further contradict the lattitude myth, the numbering
increases as you move south; lattitude increases as
you move north.
Nonetheless, given the numbering convention,
one of the highways would come close to matching
its respective lattitude number. It turns out that Route
40 is that road. It was nothing special, just numerical
coincidence.
By the way, the National Road was petitioned
to have the designation U.S. Route 1. However the highway
administration overseeing the numbering saw this as
a violation of their convention and wisely rejected
the proposal. The highway administration sought to maintain
a consistent numbering convention.
