CLIFFSIDE PARK, a borough of Bergen county, New Jer sey, U.S.A., on the Palisades overlooking the Hudson river, about opposite Tooth street in New York city. The railroad station is Weehawken (q.v.). It is a rapidly growing residential suburb, with a population of 5,709 in 1920; and was 15,267 in 1930 by the Federal census.