The newest and shortest Interstate...

theoldwizard1 wrote:
Most Interstates go "coast to coast" with odd number one running north-south and even number ones running east-west.

I-69 is a rare bird ! It has been around for quite some time now, but it runs from Port Huron (okay, sort of on a coast, with Canada) to Indianapolis, which is kind of just in the middle of IN !

You have to wonder what the initial motivation was ? (GM used to have factories in Indianapolis and Flint, through which I-69 passes, but they are all closed or sold off.)

In addition 3 digit routes:
- Even first digit routes are bypasses or loops that connect back to the main route at both ends. (I-275 bypasses Detroit for example)
- Odd first digit routes are spurs that only connect to the primary route at one end. (I-196 cuts across Grand Rapids to dead end at Holland)

Also they generally try to have lower numbers the further south and west you are (practicality sometimes causes this to be violated) I-5 runs up the west coast, I-95 up the east coas, I-10 follows the southern boarder, I-94 follows the northern.

Actually the full I-69 route runs all the way to Texas but it's not completed along it's entire length. There are additional stretches that are open. It's common for short sections to violate the direcitonality of the number.

The big reason for swinging east to Port Huron is to divert Canada bound traffic from the Detroit crossings and off I-94 which is overloaded with trucks but it's never been as popular as they hoped.

H-1 by definition is not "interstate" since it obviously only includes 1 state but politically giving Hawaii no interstate funds was politically unacceptable, so they received a special dispensation. (Alaska has a similar dispensation)