Critical question about freeways: Why do people...?

Grammatically speaking, it would sound funny to say "Take 5 north to 55 north to 91 east...", as if you are purposely leaving out words. It's like calling the Empire State Building "Empire State Building". "The" and "thee"? If the word after "the" starts with a vowel, the word is "thee". If the word starts with a consonant, the word is "the". Try it. It simply sounds funny to get it reversed. "THE 5". "THEE 805". "THEE 5". THE 805". It's even harder to say. We don't generally refer to them by name, because they change names as you drive on them. For example, the 91 starts as the Riverside freeway, and as you get closer to downtown Los Angeles, it changes to the Artesia Freeway. But it is always the 91. Same with the 5. It is the Santa Ana Freeway for a while, but changes to the Golden State Freeway. Some freeways have even changed names completely. The 55 freeway started life as the Newport Freeway, and has since become the Costa Mesa Freeway. It's just much easier and more consistent to refer to them by number. If someone tells me to take the 5 north from San Diego to Sacramento, I know exactly what they are talking about. By the way, we in So Cal refer to Northern California as "No Cal", not "Nor Cal". I have tried to answer all of your questions to the best of my knowledge. I hope I succeeded.

You kind of answered your own question. Because we used to say "The" San Diego Fwy, but now we just say "The" 405 to make it easier. The cultural habit stayed the same while the nomenclature didn't.

Its just we roll down So Cal dude.

WOW, this is serious stuff here. I bet you're one of those who says oree-gone for Oregon.

Find something worth while to lose sleep over....

Absolutely CRITICAL.