Did you like the way I ended my last post with the "more on that to come" tease? No? Didn't notice it? Oh well.
Well, here are the other immensely practical things I learned:
1) When a two-digit highway ends in an even number, it runs east-west. When it ends in an odd number, it runs north-south.
2) If a three-digit highway starts with an even number, that means that it will reconnect with the highway represented by the last two digits. That makes no sense, I know. Let's use a concrete example: the DC Beltway. It's 495, which means that it connects with I-95. Same thing with 695 in Baltimore, and 495 in Philly. Cool, eh?
3) Conversely, if a three-digit highway starts with an odd number, it means it ain't never joining forces with the highway represented by the last two digits. Think 195 (toward BWI airport) or 395 headin' into Virginia. These offshoots are called spurs.
4) If the exit number atop the exit sign on a highway is positioned to the right, then the exit will be on the right. If it's on the left, the the exit will be on the left. I haven't figured out what it means when they are in the middle.
There's nothing mind-expanding in this here post, Gentle Reader, but I likes to pass the helpful tidbits along.