Back in 2003 (in my thousandth post), in a discussion of the general phenomenon of place names with and without “the,” I mentioned the fact that Southern Californians use the definite article when referring to freeways (“the 405”), and there was some discussion of that in the thread. Now Kári Tulinius sends me a link to a Washington Monthly discussion by Kevin Drum, who provides “the long-awaited semi-official explanation for this phenomenon. It’s official because it appears in an academic journal, but only semi because I remain a little skeptical anyway”:
The article is called “The” Freeway in Southern California, by Grant Geyer, and it appeared as a note in the summer 2001 issue of American Speech. His story starts at about the time that LA’s original five freeways were being built in the 30s and 40s:
In about 1941, just before the completion of the first of the famous freeways, intercity traffic came into Los Angeles on the north-south axis on U.S. 99, U.S. 101, or California Route 1…. Before the freeways were built, locals generally preferred the old, time-honored street or road names instead of numbers in conversation. So for ‘U.S. 99’ they said San Fernando Road because the highway followed that particular named street, as far as the distant end of “town.” Likewise, ‘U.S. 101’ was Ventura Boulevard and ‘Route 1’ was Pacific Coast Highway….Route 1 or Route 101 was not used in town.
When the federal interstate system grew up, the southern California area got its share of funding and road numbers…. However, for the first 20 years of the interstate system, no one used the numerical designations…. The interstate routes around Los Angeles were called the Ventura Freeway, the Hollywood Freeway, the Santa Ana Freeway, the Golden State Freeway, the San Bernardino Freeway, the Pasadena Freeway, the Glendale Freeway, the San Diego Freeway, the Santa Monica Freeway, the Harbor Freeway, the Riverside Freeway, and the Long Beach Freeway.
….The strange-sounding usage of the plus number, as in the 118, was the natural result of an amazing proliferation of new, minor interstate cutovers, extensions, and bypasses that began about 1975…. [It] was even more pronounced when new major Los Angeles interstates sprang up without having any precursors and without being extensions of earlier, nonnumerical freeways. The first one I remember in this category was the 605 Freeway.
… My objection is that this is all pretty ad hoc. Basically, Geyer is saying that other big cities had named highways too, but they just didn’t have quite as many as LA, so the never caught on. But if all your highways have names, and that’s the original source of the, then why would it matter how many you had? You either get accustomed to referring to them by name or you don’t, and if you do, you’d be just as likely as LA to evolve to using the with a numerical designator too. But nobody else did.
An interesting theory and a cogent objection. (With regard to NYC, a commenter in the linked Washington Monthly thread says, quite correctly, “New Yorkers never bother to learn the numerical designators. I drove there daily for years, and I still couldn’t tell you what number the Van Wyck is, or the Major Deegan, or almost any of them for that matter.”) I throw the floor open to suggestions.