Kansas City, Kansas is 5.7 times larger than Manhattan (NYC borough).
Area: 332 km2 calculated
Kansas City is the third-largest city in the state of Kansas, the county seat of Wyandotte County, and the third-largest city of the Kansas City metropolitan area. It is part of a consolidated city-county government known as the "Unified Government". Wikipedia
Area: 59 km2 calculated
Manhattan is the most densely populated of the five boroughs of New York City. The borough is coterminous with New York County, an original county of the U.S. state of New York. Wikipedia