Rumson is a borough in Monmouth County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 7,122, reflecting a decline of 15 (-0.2%) from the 7,137 counted in the 2000 Census, which had in turn increased by 436 (+6.5%) from the 6,701 counted in the 1990 Census. Rumson was formed as a borough by an act of the New Jersey Legislature on March 15, 1907, from portions of Shrewsbury Township, based on the results of a referendum held on June 18, 1907.