US 104 never connected with its implied parent route (US 4), but it shared the same approximate latitude, and I do not consider its number to be a major violation of route numbering guidelines.  Its east end was at its junction with US 11 in Maple View:
Picture
c. 1943, USGS
This sign is for travelers eastbound on NY 104, at the junction where historic US 104 ended.  When US 104 was decommissioned, it became NY 104, and today that designation continues about ten miles further east than US 104 did:
Picture
Kerr
This shot was looking the opposite direction; straight ahead was the historic east beginning of US 104:
Picture
Kerr, May 2002
For maps, photos, and info relevant to US 104's historic west terminus, please see the Niagara Falls page.
Research and/or photo credits: Doug Kerr; Dale Sanderson; Michael Summa
Page originally created 2000;
last updated Aug. 17, 2019.