Californian, a World of Freeways.
This "regional feature" is actually also reflected in linguistic differences:
- "freeways" in CA are often called "highways" or "expressways" everywhere else and "interstates" (because that's what they are) in the South, and they are all essentially the same.(A highway in Clifornia seems to be for smaller roads like PCH - Pacific Coast Highway)
- when the freeways are not "free", they are called "tollways" in California and "turnpikes in the Midwest and in the Northeast.
- Then, as Kevin Drum noted this week, Southern Californians tend to use a definite article (the) when referring to freeways. Therefore you talk about "the 5", "the 405", or "the 10".This is not something you hear in the rest of the country. (you say, for instance, "take 95 to...." without the definite article).
This habit though seems not to have spread north of Monterrey.
Adding the in front of highway names seems to be a Southern California issue. In the San Francisco Bay area 'the' is almost never pre-pended, and the same applies to the Sacramento area and all of California north of San Francisco as far as I can tell. Indeed, my Southern California habits in this regard have gotten on the nerves of SF Bay Area natives more than once. (The Wash. Monthly)
- California freeways are also referred to by name. (The Santa Monica Freeway, the San Diego Freeway, etc... ) although that does not seem specially SoCal (in Chicago "expressways" are often referred to with their names, "The Edens" or "The Kennedy,")