| River Forest to Olympia (Washington) | 1,750.29 mi (2,816.82 km) |
| River Forest to Olympia Heights (Florida) | 1,195.76 mi (1,924.39 km) |
| River Forest to Omaha (Nebraska) | 427.62 mi (688.18 km) |
| River Forest to On Top of the World Designated Place (Florida) | 936.29 mi (1,506.82 km) |
| River Forest to Onalaska (Wisconsin) | 219.93 mi (353.94 km) |
| River Forest to Oneida (New York) | 624.23 mi (1,004.61 km) |
| River Forest to Oneonta (New York) | 653.53 mi (1,051.76 km) |
| River Forest to Ontario (California) | 1,700.80 mi (2,737.18 km) |
| River Forest to Ontario (Oregon) | 1,473.86 mi (2,371.95 km) |
| River Forest to Opa-locka (Florida) | 1,186.01 mi (1,908.70 km) |
| River Forest to Opelika (Alabama) | 651.89 mi (1,049.11 km) |
| River Forest to Opelousas (Louisiana) | 820.42 mi (1,320.35 km) |
| River Forest to Orange (California) | 1,719.29 mi (2,766.93 km) |
| River Forest to Orange (Texas) | 877.97 mi (1,412.96 km) |
| River Forest to Orange City (Florida) | 967.27 mi (1,556.67 km) |
