User:Juliancolton/List of counties/N-O
- Nacogdoches County, Texas
- Nance County, Nebraska
- Nantucket County, Massachusetts
- Napa County, California
- Nash County, North Carolina
- Nassau County, Florida
- Nassau County, New York
- Natchitoches Parish, Louisiana
- Natrona County, Wyoming
- Navajo County, Arizona
- Navarro County, Texas
- Nelson County, Kentucky
- Nelson County, North Dakota
- Nelson County, Virginia
- Nemaha County, Kansas
- Nemaha County, Nebraska
- Neosho County, Kansas
- Neshoba County, Mississippi
- Ness County, Kansas
- Nevada County, Arkansas
- Nevada County, California
- New Castle County, Delaware
- New Hanover County, North Carolina
- New Haven County, Connecticut
- New Kent County, Virginia
- New London County, Connecticut
- New Madrid County, Missouri
- New York County, New York
- Newaygo County, Michigan
- Newberry County, South Carolina
- Newport County, Rhode Island
- Newton County, Arkansas
- Newton County, Georgia
- Newton County, Indiana
- Newton County, Mississippi
- Newton County, Missouri
- Newton County, Texas
- Nez Perce County, Idaho
- Niagara County, New York
- Nicholas County, Kentucky
- Nicholas County, West Virginia
- Nicollet County, Minnesota
- Niobrara County, Wyoming
- Noble County, Indiana
- Noble County, Ohio
- Noble County, Oklahoma
- Nobles County, Minnesota
- Nodaway County, Missouri
- Nolan County, Texas
- Nome Census Area, Alaska
- Norfolk County, Massachusetts
- Norman County, Minnesota
- North Slope Borough, Alaska
- Northampton County, North Carolina
- Northampton County, Pennsylvania
- Northampton County, Virginia
- Northumberland County, Pennsylvania
- Northumberland County, Virginia
- Northwest Arctic Borough, Alaska
- Norton County, Kansas
- Nottoway County, Virginia
- Nowata County, Oklahoma
- Noxubee County, Mississippi
- Nuckolls County, Nebraska
- Nueces County, Texas
- Nye County, Nevada
- O'Brien County, Iowa
- Oakland County, Michigan
- Obion County, Tennessee
- Ocean County, New Jersey
- Oceana County, Michigan
- Ochiltree County, Texas
- Oconee County, Georgia
- Oconee County, South Carolina
- Oconto County, Wisconsin
- Ogemaw County, Michigan
- Ogle County, Illinois
- Oglethorpe County, Georgia
- Ohio County, Indiana
- Ohio County, Kentucky
- Ohio County, West Virginia
- Okaloosa County, Florida
- Okanogan County, Washington
- Okeechobee County, Florida
- Okfuskee County, Oklahoma
- Oklahoma County, Oklahoma
- Okmulgee County, Oklahoma
- Oktibbeha County, Mississippi
- Oldham County, Kentucky
- Oldham County, Texas
- Oliver County, North Dakota
- Olmsted County, Minnesota
- Oneida County, Idaho
- Oneida County, New York
- Oneida County, Wisconsin
- Onondaga County, New York
- Onslow County, North Carolina
- Ontario County, New York
- Ontonagon County, Michigan
- Orange County, California
- Orange County, Florida
- Orange County, Indiana
- Orange County, New York
- Orange County, North Carolina
- Orange County, Texas
- Orange County, Vermont
- Orange County, Virginia
- Orangeburg County, South Carolina
- Oregon County, Missouri
- Orleans County, New York
- Orleans County, Vermont
- Orleans Parish, Louisiana
- Osage County, Kansas
- Osage County, Missouri
- Osage County, Oklahoma
- Osborne County, Kansas
- Osceola County, Florida
- Osceola County, Iowa
- Osceola County, Michigan
- Oscoda County, Michigan
- Oswego County, New York
- Otero County, Colorado
- Otero County, New Mexico
- Otoe County, Nebraska
- Otsego County, Michigan
- Otsego County, New York
- Ottawa County, Kansas
- Ottawa County, Michigan
- Ottawa County, Ohio
- Ottawa County, Oklahoma
- Otter Tail County, Minnesota
- Ouachita County, Arkansas
- Ouachita Parish, Louisiana
- Ouray County, Colorado
- Outagamie County, Wisconsin
- Overton County, Tennessee
- Owen County, Indiana
- Owen County, Kentucky
- Owsley County, Kentucky
- Owyhee County, Idaho
- Oxford County, Maine
- Ozark County, Missouri
- Ozaukee County, Wisconsin
