| Sliven to Olympia Heights (Florida) | 5,804.93 mi (9,342.13 km) |
| Sliven to Omaha (Nebraska) | 5,617.77 mi (9,040.93 km) |
| Sliven to On Top of the World Designated Place (Florida) | 5,723.47 mi (9,211.04 km) |
| Sliven to Onalaska (Wisconsin) | 5,319.89 mi (8,561.53 km) |
| Sliven to Oneida (New York) | 4,796.84 mi (7,719.76 km) |
| Sliven to Oneonta (New York) | 4,801.09 mi (7,726.61 km) |
| Sliven to Ontario (California) | 6,666.50 mi (10,728.69 km) |
| Sliven to Ontario (Oregon) | 6,031.00 mi (9,705.96 km) |
| Sliven to Opa-locka (Florida) | 5,792.67 mi (9,322.40 km) |
| Sliven to Opelika (Alabama) | 5,674.58 mi (9,132.36 km) |
| Sliven to Opelousas (Louisiana) | 6,048.06 mi (9,733.40 km) |
| Sliven to Orange (California) | 6,686.52 mi (10,760.91 km) |
| Sliven to Orange (Texas) | 6,133.65 mi (9,871.15 km) |
| Sliven to Orange City (Florida) | 5,689.35 mi (9,156.13 km) |
| Sliven to Orangeburg (South Carolina) | 5,450.24 mi (8,771.32 km) |
