Keansburg (pronounced "KEENS-burg") is a borough in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 10,105, which represented a decline of 627 (-5.8%) from the 10,732 counted in the 2000 Census, which had in turn declined by 337 (-3.0%) from the 11,069 counted in the 1990 Census.
Keansburg was formed as a borough by an act of the New Jersey Legislature on March 26, 1917, from portions of both Middletown Township and Raritan Township (now Hazlet), based on the results of a referendum held on April 17, 1917.
The borough is part of the Bayshore Regional Strategic Plan, an effort by nine municipalities in northern Monmouth County to reinvigorate the area's economy by emphasizing the traditional downtowns, dense residential neighborhoods, maritime history, and the natural beauty of the Raritan Bay coastline.
The land that is now Keansburg was earlier home to Lenni Lenape Native Americans.
On September 3, 1609, the Half Moon, captained by Henry Hudson, is said to have landed on the shores of present-day Keansburg (although some historians argue that the landing and forthcoming explained events took place at the tip of Sandy Hook). Crewmen of the ship were attacked by the Native Americans when they departed the ship, and John Colman was killed, making him what is said to be the first European to be felled by a Native American arrow. He is believed to have been buried in the area that is today the intersection of Carr Avenue and Beachway in an area known as "Colman's Point".
In the time between 1609 and the early 18th century, the land was gradually purchased from the Lenni Lenape, together with other surrounding areas. The area was inhabited by Dutch, English, and Scottish settlers. In the 18th century, farming proved to be successful on Keansburg's land, with specialties being pears, apples and corn (maize).
In this time, the settlement took on the name of Waackaack (pronounced "Way-kay-ack"), which came from the term "Wakioak" in the Lenape language meaning "Land of Plenty". The area was also widely known as Tanner's Landing from the early 18th century until approximately 1820, so named for the pier at the end of what was Tanner's Landing Road (now Main Street).