Dover Plains is a hamlet and census-designated place in Dutchess County, New York, United States. The population was 1,323 at the 2010 census. It is part of the Poughkeepsie–Newburgh–Middletown Metropolitan Statistical Area.Dover Plains is in the northern part of the town of Dover on NY Route 22.Metro-North Railroad has a Harlem Line station here, bringing commuters to New York City. This station was the line's northern terminus until 1852 when the line was carried farther north to Chatham.