I know that, for federal highways at least, roads with an odd-number designation (I-95, for example) run north/south, and roads with an even-number designation (I-64, for example) run east/west. My question is more about how the number designation got started in the first place. Was US Route 1 the first such road designated (I know that US Route 1 has been in existence a lot longer than the numbering scheme, so the scheme doesn’t revolve around construction)and the Federal Highway Administration, being the rational, engineering types that they are, just kept on with the numbering system?
The U.S. Route numbering system was created back in the 1920s as a way of creating a unified system marking routes from state to state. The original U.S. routes were laid over existing roads for the most part, unlike the Interstates which were often built from scratch outside the major cities. Nowadays most “U.S.” routes are paid for and maintained by state governments, not the Feds.
There is a logic to the U.S. numbering scheme as well, odds go north/south, evens go east/west, low numbers in the north and east, high numbers to the south and west. There are a few oddballs and exceptions.
As another example, U.S. 40 from Maryland to Illinois is the old “National Road” and was built way back in the 1840s or 1850s, but never had a number until the 1920s. Before the numbering system most roads had names instead of numbers and the names were often different from state to state and even from county to county inside a state. That probably made asking for directions at the local gas station all the more confusing…
sorry but that’s back asswards. The lower numbers are in the south, 10 runs from Jacksonville to LA, I think, and 70 runs from Baltimore to the middle of Nevada or something. 95 runs from Maine to Florida.
It works just like a Cartesian (sp?) plain, just like most state highway milage markers.
You’re both right. Check What’s the significance of interstate highway route numbers?.
To sum up, interstate highway numbers are as Edward the Head describes, lowest in the south and west. They were done that way specifically to avoid confusion with the older U.S. Route numbers that fiddlesticks is talking about.