 The LIRR opened the Sag Harbor Branch, including the present Montauk Branch from Eastport to Bridgehampton, on June 8, 1870.On July 27, 1881, after the South Side became part of the LIRR, its line – then the Montauk Division – was extended east to the Sag Harbor Branch at Eastport.The Sag Harbor Branch east of Eastport became part of the Montauk Division, and the old line from Manor (Manorville) to Eastport became the Manor Branch.