Question: What is the name of the region that includes the cities Dover and Portsmouth, New Hampshire?

The Portsmouth, Great Falls and Conway Railroad (PGF&C) (later known as the Conway Branch of the Boston and Maine Railroad) is a former rail line between Rollinsford and Intervale, New Hampshire, in the United States.  At Rollinsford, the line connected to other lines to provide service between the White Mountains and coastal cities such as Boston.  At Intervale, it connected to the Mountain Division of the Maine Central Railroad.  The rail line takes its name from the city of Portsmouth, near its southern terminus; the city of Somersworth (formerly known as "Great Falls"); and the town of Conway, near its northern terminus.  Today, the infrastructure of the former PGF&C is owned by different entities, including the State of New Hampshire, the Conway Scenic Railroad, and the New Hampshire Northcoast Corporation.  Some segments are still operated as freight or heritage railways, while other segments are being maintained as rail trails. <SEP>  The region stretches 13 mi along the Atlantic Ocean from New Hampshire's border with Salisbury, Massachusetts to the Piscataqua River and New Hampshire's border with Kittery, Maine.  The shoreline is generally very rocky and rough in nature, although a few sandy beaches have been created using jetties/groins, particularly in the towns of Rye and Hampton.  The Seacoast Region stretches as far west as Epping. The Seacoast Region is the southeast area of the U.S. state of New Hampshire that includes the eastern portion of Rockingham County and the southern portion of Strafford County.  Portsmouth, the largest municipality and only city in Rockingham County, serves as the cultural and commercial hub of the region.  Portsmouth has numerous historical landmarks and tourist attractions including Strawberry Banke, the Moffatt-Ladd House, the John Paul Jones House, and the Portsmouth Children's Museum, which moved to Dover in 2010.  The Seacoast Region was the first area of the state to be permanently settled by Europeans in the early 17th century. <SEP>  The population was 29,987 at the 2010 census, the largest in the New Hampshire Seacoast region.  The population was estimated at 31,153 in 2016. Dover is a city in Strafford County, New Hampshire, United States.  It is the county seat of Strafford County, and home to Wentworth-Douglass Hospital, the Woodman Institute Museum, and the Children's Museum of New Hampshire. <SEP> Norfolk County, Massachusetts Colony was one of the original four counties created in the Massachusetts Bay Colony.  The land was originally granted as separate from Massachusetts, but boundary disputes among the settlers led to their petitioning to join the colonial government to the south.  The county was created by the Massachusetts General Court on May 10, 1643, when it was ordered "that the whole plantation within this jurisdiction be divided into four sheires".  Norfolk County contained the settlements of Salisbury, Hampton, Haverhill, Exeter, Dover, and Portsmouth.  It effectively encompassed all settlements from the Merrimack River, north to the Piscataqua River, and extending inland about a dozen miles.  In 1680, the Province of New Hampshire was formally separated from Massachusetts, with Norfolk County forming the core.  Massachusetts retained the northern bank of Merrimack River and the towns of Salisbury and Haverhill were added to Essex County.  Hampton, Exeter, Dover, and Portsmouth were governed at two levels, town and province/colony, until 1769, when New Hampshire was itself divided into counties, so that Norfolk ceased to exist.