"Newfoundland" is a locality like Oak Ridge and Milton, to name a few in the immediate area. The U.S. Post Office known as Newfoundland serves customers in both West Milford Towship (Passaic County) and Jefferson Township (Morris County). The Post Office does not necessary conform to existing state and local boundries. (There are a number of people in Montague NJ whose address is Port Jervis NY. Talk about confusion!)
In fact, Jefferson Township NJ doesn't even exist from the viewpoint of the Post Office. The residents there are served by the Newfoundland P.O. in the north end, and the Lake Hopatcong P.O. in the south. I think even a few people get their mail from Sparta.
So the area generally surrounding the station in both towns is known as Newfoundland, and like most localities, there is no specific line between where Newfoundland ends and where, say, Echo Lake or Smiths Mills, two other localties, begin.
That said, and while more of Newfoundland is probably in West Milford, the station is indeed on the Jefferson Twp./Morris County side of the Pequannock River.
(As an aside, when rivers and streams are used to mark boundries between towns and states, they are often at the mercy of Mother Nature. Many of these waterways change course over time, sometimes a few feet, sometimes miles in the case of the Mississippi. That's why despite a 3-mile wide river separating them, it is possible in many places to walk between Arkansas and Kentucky, or Louisiana and Mississippi. Hell on mapmakers, and even more on tax assessors!)
"But Dad. It's Smokey!"
