I'm local to Tenafly, NJ zip 07670 and I found what I consider the steepest hill in my area.
It is on Elm Ave zip code 07657 (corner of Bergen Blvd and Elm Ave).
Unfortunately, this is a regular street so you do have to be careful and not that long, but it feels extremely steep. (Wasn't even sure if car was going to struggle!)

Looking for more hills please!