(Spoiler: NY was "Search by State", CA/TX was "Zip + radius")
(Spoiler: NY was "Search by State", CA/TX was "Zip + radius")
That said, I’d take Suffern NY over south Jersey, so by state isn’t ideal either.
Population density means zip codes are extremely concentrated in NYC, especially in Manhattan. Traveling down the length of Manhattan might have you cover ~25 zip codes in 13 miles. Basically, a zip code isn't a meaningful measure of distance like it might be elsewhere. A radius might also place you into NJ, which could be an issue depending on what you're trying to accomplish: Delivering something from Queens might be significantly easier than from NJ, even though Queens might be further.
That's my guess anyway, though it's odd because nowadays generally looking something up via zip code + radius is actually easier in Manhattan (with a map you can easily see whether it would require coming from Jersey, crossing the park, etc. etc.)
Contrast to FL, TX, CA, and we had to immediately support zip-code-ish search (a non-trivial technical and operational burden, as zip-codes are rough-approximates for GEO's, and change pretty frequently) b/c "Couch for Sale in TX" means something completely different from "Couch for Sale in MA".
Contrast to the midwest (eg: kansas, montana), and this random-population-density-map I found: http://ecpmlangues.u-strasbg.fr/civilization/geography/US-ce...
...you can see that "just tell me what state it's in" hits within ~1hr of a single city center up until you hit TX or FL. So in 2000 it was a reasonable shorthand for "east-coasters" to say: "MA == Boston of course", and "CO == Denver" b/c where else was the internet going to be? ...either relatively close-by, or at your states major population center.
This is totally non-scientific and anecdotal, but I worked for a P2P sales startup out of college, implemented the zip-code search, radius, and update code, and distinctly remember noticing that some competitors (and dating sites!) definitely didn't support zip + radius searching, and they were usually ones that were funded from NY. CA was probably a bit more technically advanced, geo-aware, and wouldn't usually launch w/o zip + radius capabilities... again b/c "Couch in NV/CA", or "Singles in NV/CA" is a completely different scale from "Couch in NY/NJ, or Singles in NY/NJ"
(edit: in the 2000-era!! barely dial-up, and computers in general were decidedly non-rural devices, no cellular networking, and a motorola "two-way" was peak connectivity).