N.Y. State Law § 8

§ 8. Maintenance of monuments. The commissioner of transportation, in\ncooperation with persons duly authorized by the adjoining state, shall\ncause the monuments erected, or to be erected, as boundaries of the\nstate, to be maintained, and cause suitable monuments to be set wherever\nsuch are now lacking at the points where such state boundary is\nintersected by the boundary of any towns or counties of this state, or\nby any highway.\n