The borough of Rumson was formed by an act of the New Jersey Legislature on March 15, 1907, from portions of Shrewsbury Township, based on results of a referendum held on June 18, 1907. Rumson was originally purchased by English settlers in pieces. The first purchase was dated January 25, 1665, and it included parts of Middletown. The rest of the area was purchased later that year. Legend has it that the borough's name is derived from early settlers who bought the land from the Native Americans in exchange for some rum. But as far back as 1663, long before the area was officially named Rumson, Native Americans called it "Navarumsunk". Over the years it has been shortened to "Rumson", though sources also talk of a Chief Alumson as a source of the name. Other names Rumson has been known by include Black Point, Port Washington, and Oceanic.
Source: Snyder, John P. The Story of New Jersey's Civil Boundaries: 1606-1968, Bureau of Geology and Topography; Trenton, New Jersey; 1969. p. 184.