Closter () is a borough in Bergen County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 8,373, reflecting a decline of 10 (-0.1%) from the 8,383 counted in the 2000 Census, which had in turn increased by 289 (+3.6%) from the 8,094 counted in the 1990 Census.
The Lenni Lenape Native Americans tilled the soil, hunted in the woods, and fished in the rivers and streams before the Dutch arrived in the early 18th Century. The Dutch settlers, though, left an indelible mark on the area. Early records show that after the English takeover of New Netherland, English Governor Philip Carteret in 1669 granted a real estate speculator named Balthaser De Hart a strip of property which extended east and west from the Hudson River to the Tiena Kill, and north and south from today's Cresskill into Palisades, New York. It is within these geographical boundaries that lies what is now known as Closter. The first land grant deed for the area today known as Closter was not written until April 13, 1671. The northern half of this tract of land consisting of 1,030 acres (420 ha) (extending from what is Closter Dock Road northward) was purchased by Barent and Resolvert Nagel on April 25, 1710, who along with the Vervalen family first settled what is now Closter.
The name Closter is of Dutch origin and first appears in a November 18, 1721 deed between the surviving Tappan Patentees and Peter Haring (who owned land in Harrington Park/Norwood east of Tappan Road and between Harrington and Blanche Avenues) - the meets and bounds of the deed begin “Beginning at the bridge which comes out of the Clooster by the Dwars Kill . . ." (At that time, Closter was considered part of New York State). In the Dutch language, Klooster or "clooster" means "a quiet place, a monastery or cloister."
The name was originally pronounced with an "ow" sound, phonetically, "Klowster."
The topography gave a sense of isolation and protection, tucked behind the highest point of the Palisades and protected by limited access.