How U.S. interstate highways are numbered - GIF

How U.S. interstate highways are numbered.

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Previously:

1951 highway construction - GIF
Car catapults off highway - GIF
Chain reaction highway truck crash - GIF
Dump truck caught by overhead highway sign - GIF
Freight train crossing a 7-lane highway - video

I always knew that east and west were even, and north and south were odd. I didn't know the rest. That's pretty interesting.