But people eventually found the numbers more pertinent to travel, so that's what won.

Route numbers didn't have that effect on streets. I've never once heard anyone refer to Santa Monica Boulevard as Route 2. (Or "The 2" or "Two.")

I don't remember which on-ramp it is, but there's one in the Valley that has all 4 directions marked to the 101. One direction, the signs say north/south, the other direction they say east/west.

I ran into this navigating on my one day in SD. I knew where I was, and where I wanted to go, but the streets didn't go there. I even knew where I ended up, and I could have found my way to Old Town from there. I wound up asking a blind guy for directions and he advised me to take the bus which turned out to be good advice.

Because the freeway system became so prominent in SoCal. There are many places in California (not to mention the rest of the US) where surface street routes are still called by the route number. When I was growing up in OC, Beach Blvd was always referred to as "Highway 39", and I can remember when PCH was just called "Highway 1". Just because the practice is no longer common does not mean it wasn't common in the past.

(ETA because I thought of this seconds after hitting "submit reply".)

When my parents talked about moving to California in the 50's, they talked about driving into LA on Route 66, and never mentioned the names of all the streets that comprised Route 66 in Southern California.

My dad and his family drove to CA on Route 66.

Bought him a great coffee table book about it.

One of these days I want to go back east, taking what's left of it.

Now I have an urge to watch Cars

Did someone already mention the need for a reliable van?

Not needed. I have a 2008 Honda accord with only 6k miles on it. Reliable transportation is not at issue.