Castaic is considered to be the northern end of Santa Clarita. This is in debate.
While being the supposed boundary of Santa Clarita, it is also the boundary of civilization in the area. When going north on the golden state freeway, Castaic is the last thing you'll see for 300 miles (literally).
Once in the city of castaic, its always rush hour, no matter what time to go in. You'll always be going 15 mph in 45 zones due to the idiot truck drivers that take so long to make a left turn that by the time its done, it's run 2 red lights while your stuck with the on coming traffic that had to stop for it.
Guy 1: Guess what? I live in castaic!
Guy 2: (gunshot)
Guy 1: Ow! What the hell?