Who or what determines the responsibilities of a shared road between two municipalities?
Normally when a road is on a shared boundary there is an agreement detailing who does the maintenance and has ownership (including the subsequent requirements for maintenance and associated CHIPS funding). There should be a copy of the agreement file with the clerk’s offices in each respective municipality.
Sections 182 and 187 of NYS Highway Law detail the legal issues on the matter.
NYS Highway Law 182
NYS Highway Law 187