Yeah, King Co is laid out that way, but no where else I've lived is. SLC was close, but they tended to go from each city center, even the small towns, so you rarely saw numbers over 10000. Most of central/west CO that I've been in is like SLC, with each town having it's own geographic center for the grid numbering, so the numbers don't *usually* get that high. It was one of those things that I noticed in the show, figured was an injoke of some sort, or Da Boyz imprinting a county-wide grid system on South Park, but never thought the numbers *meant* anything that might be discernable by the general populace.

Unfortunately, there is no zip code in the US of (I think it was) 41795, which was another house, so... *shrug*

Who knows, maybe it was sheer coincidence, but somehow I don't think so. :)