Monroe County is located in northwestern New York . It is the home to the metropolitan city of Rochester, which has a significant portion of Monroe County's population. Monroe County has a total area of approximately 1366 square miles of which 49% is land and 51% water. Currently Monroe County has the sixth largest population in New York State. As of the census of 2000, there were 735,343 people, 286,512 households, and 184,513 families residing in the Monroe County. To the north of Monroe county is Lake Ontario, one of the five Great lakes of North America.