Plainview is a hamlet and census-designated place (CDP) located near the North Shore of Long Island in the town of Oyster Bay in Nassau County, New York, United States. The population of the CDP as of 2010 was 26,217. The Plainview post office has the ZIP code 11803.
Plainview and its neighboring hamlet, Old Bethpage, share a school system, library, fire department, and water district. Law enforcement for the communities is provided by the Nassau County Police Department's Second Precinct.
Plainview is located at 40°46′48″N 73°28′46″W (40.779911, -73.479483).
According to the United States Census Bureau, the CDP has a total area of 5.7 square miles (15 km2). Plainview is on the Nassau County side of the border with Suffolk County. On the Nassau side it borders the hamlets of Hicksville, Old Bethpage, Syosset, and Woodbury. On the Suffolk side, its primary border is with Melville, but also touches West Hills.
Plainview's origins dates to 1648, when Robert Williams, a settler from Wales, bought land in the area. The land was considered desirable for farming because of a small pond named the Moscopas by local Native Americans, meaning "hole of dirt and water".