

How about drawing a grid on the entire country, and labelling each new square state in chessboard style? American streets try to be sensible and consistent like that, so why not just apply the same idea on a federal level too? If you’re in the state D5, you’ll know that D4 right next door.

Logical consistency. Americans were so good at this when building the place. Look at the farm plots on a map. Streets in the city center usually form a neat grid. Even the highway system makes sense for the most part.
Meanwhile in Europe we were just winging it and letting things grow more or less organically. Has worked just fine for 1000+ years so it’s too late to change it now.