"Surely the city of New York is not in California?"
Translation:Num urbs Novum Eboracum in California est?
That would mean "the city that belongs to New York". The English sentence could just as well have been "surely the city New York is not in California"
There is no Novi Eboracus as far as I know, but Novum Eboracum and Novi Eboraci (in New York).
Why does "Philadelphiae" work as a location marker but not "Californiae"?
The locative case is only used with the names of cities, towns, and small islands.
Thanks! In school, locative wasn't of much prevalence because we mostly only translated into German, not vice versa. The Latin originals didn't have many locatives to offer as far as I remember.