 The roadway connecting Horseshoe Lake to Tupper Lake was built and became part of NY 421 by 1968.NY 421's former routing to Warren Point remained a state highway up through 1999, when a bill permitting the New York State Department of Transportation (NYSDOT) to remove it from the state highway system was signed into law.NY 421 begins at a dead end south of the hamlet of Horseshoe in an isolated part of the town of Piercefield.