"The" 40

I'm watching (sort of) this new War of the Worlds - no, not the Tom Cruise one, this I can already tell kind of cheesy 2005 Sci-Fi channel remake with C Thomas Howell. Anyway, supposedly they live in Virginia - in Greensboro. Our hero is trying to make it to DC to meet up with his wife, but the bridge is out and he can't get to Hopewell. As he stands there, all baffled, a woman walks up to him and informs him that the bridge is out, that "the terrorists got DC and the big cities first off", and that she herself is "gonna walk west, to the 40, and down to Tennessee."

And despite her quaint drawl, I don't believe for a minute that she's from around Greensboro. Not with that "the" in front of I-40's name.