Sagamore is a census-designated place (CDP) in the town of Bourne in Barnstable County, Massachusetts,United States. The population was 3,623 at the 2010 census.Sagamore is located in the northeastern corner of the town of Bourne. It is bordered to the northeast by Cape Cod Bay, to the northwest by the town of Plymouth, to the west by the Massachusetts Route 3 expressway, to the southwest and south by U.S. Route 6 (the Mid-Cape Highway), and to the east by the town of Sandwich. The northern half of the CDP, along the shore of Cape Cod Bay, is known as Sagamore Beach. The Cape Cod Canal passes east to west through the southern part of the CDP. The Sagamore Bridge, carrying Route 6, crosses the canal in its namesake neighborhood.According to the United States Census Bureau, the Sagamore CDP has a total area of 3.5 square miles (9.1 km2). 3.3 square miles (8.6 km2) of it is land, and 0.19 square miles (0.5 km2) of it (5.10%) is water.