I-99 is particularly aggravating because of how it came into existence. At least I-238 exists by necessity. I-99 has its number because a showboating Congressma

I-99 is particularly aggravating because of how it came into existence. At least I-238 exists by necessity. I-99 has its number because a showboating Congressman snuck the number in as a rider on a bill because he thought "highest possible two-digit interstate" would get his state some more tourism. As such, I-99 is the only interstate AASHTO is forbidden by law from renaming.