Why no I-60? One would think that a major number like 60 would have been assigned.
A “Major Number”?
It’s possible that the place where I-60 would be has a state or US highway with the number 60.
There’s no I-50 either. But US 50 is a famous road. Or at least was a famous road.
There is a US 60 that runs just north of I-40 in most places.
Under the Intersate highway numbering system, major east-west Interstates that cross the country are given two digit numbers that end in zero. Two-digit numbers that end in zero or five cannot be assigned to relatively short Interstate highways.
The major east-west corridors today are I-10, I-20, I-40, I-70, I-80 and I-90. Why create a corridor that won’t serve any pressing need just to accomodate an I-50 or I-60? Considering today’s Interstate numbering system and the corresponding corridors, an I-50 and I-60 placed between I-40 and I-70 would serve almost no major metropolitan areas.
Well, they made a movie about it.
Absolutely. But . . . why not just number from 10-60 without skipping in the first place.
Presumably to leave room for expansion.
So you can get the full range of two digit numbers that end in zero going from the south to the north. This allows you to stick new roads in between existing ones from time to time, if, say, a new metropolis were to spring up in Nebraska.
From the misc.transport.roads FAQ:
That may still happen. Back when US 400 was designated in Kansas and Missouri, some lawmakers wanted to upgrade it to interstate standards and call it I-60. That’s off the table now, but a “Trans-America Corridor” project including US 400 is still bouncing around the Department of Transportation. Officially, it’s High Priority Corridor number 3.
Right now it looks like lawmakers want to name the project (assuming it ever gets built, which it probably won’t) I-66, but the aforementioned AASHTO will probably push for I-60 as it would certainly be considered “a major route.” The plans call for a Washington, D.C.-to-Los Angeles interstate, passing through very rural sections of Kansas, Oklahoma, and the western states. Good luck getting that one approved, guys. Then again, if Bud Shuster can get I-99 approved, anything is possible.