Thursday, March 21, 2013

40th Parallel


Colfax Avenue is part of U.S. Route 40. Some people believe that U.S. Route 40 obtained its numerical designation because it approximated the 40th parallel latitude 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)
If east-west transcontinental highways obtained their designation based on their latitude, all of our east-west highways would be numbered 30-48. To further contradict the latitude myth, the numbering increases as you move south; latitude increases as you move north.
Nonetheless, given the numbering convention, one of the highways would come close to matching its respective latitude 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.
Here's another coincidence - Route 40 crosses the 40th parallel four time: 1) Brownsville, Pennsylvania, 2) Cambridge, Ohio, 3) Granby, Colorado and 4) Lovelock, Nevada.

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