Place
- Old Mill Creek, Illinois1
- Olympia Fields, Illinois1
- Orland Hills, Illinois1
- Orland Park, Illinois1
- Oswego, Illinois1
- Palatine, Illinois1
- Palos Park, Illinois1
- Park City, Illinois1
- Park Forest, Illinois1
- Park Ridge, Illinois1
- Peotone, Illinois1
- Phoenix, Illinois1
- Pingree Grove, Illinois1
- Pistakee Highlands, Illinois1
- Plainfield, Illinois1
- Plano, Illinois1
- Plattville, Illinois1
- Plum Valley, Illinois1
- Port Barrington, Illinois1
- Posen, Illinois1