sometimes defined as parts of smaller metropolitan statistical areas of New Jersey. The Delaware Valley is another area that is associated with some parts of Central Jersey, specifically Mercer County. Yet despite the County’s close geographic proximity to Philadelphia's combined statistical area, Mercer County is considered part of the New York Combined Metropolitan Statistical Area as defined by the United States Census Bureau. Some parts of Hunterdon County associate themselves with the Delaware Valley and the Philadelphia Area, although Hunterdon County isn't geographically defined in this area. The New Jersey Department of Tourism places Middlesex and Union in the Gateway Region and Mercer in the Delaware Valley. Monmouth and Ocean counties are considered part of the Jersey Shore, while Somerset and Hunterdon counties are part of Skylands Region. The Raritan Valley is the region along the middle reaches of the Raritan River and its North Branch and South Branch. The Raritan Valley includes the communities of Branchburg, Bridgewater, Somerville, Raritan, Hillsborough, Franklin, Green Brook, North Plainfield, Bound Brook, and South Bound Brook, all in Somerset County; Dunellen, Middlesex, Piscataway, South Plainfield, Highland Park, New Brunswick, East Brunswick, Edison, and Metuchen, all in the northern and central portions of Middlesex County; and Plainfield in southwestern Union County. The Raritan Bayshore is used to describe the region in Middlesex and Monmouth Counties, located along the coastline of the Raritan Bay, from the mouth of the Raritan River in the west to the barrier island of Sandy Hook bordering the Atlantic Ocean in the east. The Raritan Bayshore includes the communities of Sayreville, Woodbridge, Perth Amboy, South Amboy, and Old Bridge, all in northeastern Middlesex County; Aberdeen, Matawan, Keyport, Union Beach, Hazlet, Keansburg, Holmdel, Middletown, Atlantic Highlands, and Highlands, all in northern Monmouth County. The telephone area codes 732 and 848 includes Middlesex, Monmouth, Somerset, Union, and northern Ocean counties. At least two counties in Central Jersey carry official nicknames: Mercer County is known as "The Capital County" and Middlesex County carries the nickname "The Greatest County in the Land". Colonial era Between 1674 and 1702, in the early part of New Jersey's colonial period, the border between West Jersey and East Jersey ran diagonally across the middle part of the state. The Keith Line, as the demarcation is known, ran through the center of what is now Mercer County. This border remained important in determining ownership and political boundaries until 1745. Remnants