Harlem is located in Upper Manhattan, often referred to as "Uptown" by locals. The three neighborhoods comprising the greater Harlem area—West, Central, and East Harlem—stretch from the Harlem River and East River to the east, to the Hudson River to the west; and between 155th Street in the north, where it meets Washington Heights, and an uneven boundary along the south that runs along 96th Street east of Fifth Avenue, 110th Street between Fifth Avenue to Morningside Park, and 125th Street west of Morningside Park to the Hudson River. "Encyclopædia Britannica" references these boundaries, though the "Encyclopedia of New York City" takes a much more conservative view of Harlem's boundaries, regarding only central Harlem as part of Harlem proper.