Yes, we've done this debate countless times, and the best answer is probably still "in your TV" but I just noticed a little detail that narrows down the location of Lawndale very clearly (as if the hurricane wasn't enough).
I think I can say with authority that if there is, indeed a specific location for Lawndale, it is _not_ California. I am currently watching "tape 3" of my collection, with "Quinn the Brain" showing. Helen is about to use a "when I was in high school" story to demonstrate the importance of effort to Quinn, who promptly shrieks, "Not again!" in reference to Mr. O'Niels own story. "Huh?" Helen says, to which Daria replies, "Mom, if you're going to reminice, I'm going to have to call Social Services." If they were in California, she would've referred to CPS (Child Protective Services). So, wherever Lawndale is, it isn't in California.
On another, completely unrelated note, I will not be participating on this newsgroup for quite some time. I am currently enrolled in a Trucking school, which has nine hour days and _lots_ of homework. No time. See you all in eight weeks (or sooner, if I find time...) :)