Although technically in 3 states, I’m gonna file this one under New York for 2 reasons. Nearly half the marker is in NY, so percentage-wise, NY wins. Also, you pretty much have to go through NY to get to the marker.
Underneath the bridge on Route 84 between PA & NY, it’s possible to stand in those states, along with New Jersey, at once. This is one of several tri-state points in the country. To get to this one, you have to drive through a cemetery in New York (unless you have a boat or feel like swimming in the Delaware).
Right next to the road is a marker for the NJ/NY border. The tri-state marker is past it a bit, down closer to the river. For whatever reason, this marker had a bunch of melted candles at its base and is pretty badly trashed, while the tri-state one is relatively untouched.
The tri-state monument is much smaller and has the 3 states’ borders on its top. Stand on it and you’re in all 3! Amaze your friends!
You’re the man now, dog!