California has A LOT of roads given its size, and density is focused in the big cities, so you have a lot of country roads to maintain with limited revenue to maintain them.
A lot of highways in California have warnings like "no services for 100 miles" and you won't encounter a lot of other vehicles (similar to Nevada and Oregon adjacent).
California started building a state highway network before the east cost did - also it has mountainous roads that have restrictions on overall length, simply because of curve radius.
The first freeway ever was made in California. California is a huge state with widely dispersed population centers (since well before cars), and population growth only really took off around the time of WW2 and the widespread production and adoption of cars and trucks. It’s had a very road and car centric culture since then.
Differences are typically that a freeway is designed and constructed to allow maximum speed and no interruptions/stops (hence all the on/off ramps, lack of lights, lack of toll booths), and is available to the general public for use without significant restrictions or costs.
Which make it far easier to use, faster, etc. the interstate highway system was designed largely using the model.
AFAIK only in California are toll-free, multi-lane highways called "freeways," so there may be no end to the definition-jockeying. If maximum speed is a necessary factor then CA may have no freeways at all remaining.
Haha, yeah the whole ‘high speed’ thing is pretty much only at 2am on a Wednesday in many parts of California now.
One key thing at the time I believe was the grade separation/right of way stuff, which I think had only occurred on toll roads for any distance before.
Previously almost all highways ended up having to stop or intersect with other roads (and hence stop signs, or traffic lights, or whatever). Most highways are still that way, outside of major arterials.
Most major arterial highways are the same as freeways now everywhere of course, but I think that’s more about economic factors. California I think was just the first mover on it (and got exposed to those same economic factors earlier than most).
At the time (and still does, though it gets less press now), California was a huge oil state, and was at the forefront of designing and building refineries too.
What makes the road network in CA so old compared to eastern states that had roads built so much earlier?