Ellendale is a town in Sussex County, Delaware, United States. The population was 381 at the 2010 census, an increase of 16.5% since 2000. It is part of the Salisbury, Maryland-Delaware Metropolitan Statistical Area. Ellendale is the "Gateway to Delaware's Resort Beaches" because it is the town located on U.S. Highway 113, the resort area's westernmost border, and Delaware Route 16, the resort area's northernmost border with the eastern border being the Delaware Bay and Atlantic Ocean and the southern border being the state line with Maryland.
Ellendale started as a forest and swamp on the divide between the Chesapeake Bay and Delaware Bay. The swamp was the hunting grounds of the Nanticoke Indian Tribe until they were driven out by the Lenni Lenape Tribe on the Battle Green near Chestnut Ridge, a hill on Ellendale's north side. The Lenape Trace, a main thoroughfare of a trail, passed through Ellendale as a Native American trade route from Pocomoke City, Maryland to Marcus Hook, Pennsylvania. With the arrival of Europeans, the Ellendale area was a province of fur traders and hunters. Early in the 18th century, farming and timbering pushed back the swamp that once covered the area. The tract of land on which the town would later be built was originally deeded in 1740 as "Bennett's Pleasure".
The "Nanticoke Swamp," as the Ellendale Swamp was then called, was depicted as a place where criminals routinely hid from the law in the depositions of a 1759 murder that occurred.