In 1971, when NYSDOT obtained AASHO's approval to decommission US 104, they described its west terminus as I-190, so apparently by then it no longer went all the way into Niagara Falls. Does anyone know when NYSDOT truncated the segment between Niagara and Lewiston? I don't see anything in the AASHTO archive showing that they cleared it with AASHO (which seems odd, because in 1961 NYSDOT did get AASHO's approval to extend the other terminus of US 104 from US 11 to I-81).
Interestingly, NY 104 still extends from Lewiston south into Niagara Falls. The current western terminus is at NY 384 (https://maps.app.goo.gl/pG4i7UJxzHRDb3gs9), just a block from the Rainbow Bridge in the heart of downtown Niagara Falls USA.
The US/NY 104 interchange with Ridge Rd. undoubtably was constructed with the construction of the Niagara Scenic Parkway, but does anyone know when the NY 18 Creek Rd. Extension was constructed? I imagine NY 18 terminated at US/NY 104 prior to that.