| San Marcos to Oakleaf Plantation (Florida) | 2,078.89 mi (3,345.65 km) |
| San Marcos to Oakley (California) | 420.85 mi (677.30 km) |
| San Marcos to Oakton (Virginia) | 2,245.46 mi (3,613.72 km) |
| San Marcos to Oakville (Missouri) | 1,543.19 mi (2,483.52 km) |
| San Marcos to Oatfield (Oregon) | 895.90 mi (1,441.81 km) |
| San Marcos to Ocala (Florida) | 2,079.14 mi (3,346.06 km) |
| San Marcos to Ocean Acres (New Jersey) | 2,404.14 mi (3,869.09 km) |
| San Marcos to Ocean City (New Jersey) | 2,388.78 mi (3,844.38 km) |
| San Marcos to Ocean Pines (Maryland) | 2,363.48 mi (3,803.65 km) |
| San Marcos to Ocean Pointe (Hawaii) | 2,620.86 mi (4,217.87 km) |
| San Marcos to Ocean Springs (Mississippi) | 1,673.01 mi (2,692.45 km) |
| San Marcos to Oceanside (California) | 9.92 mi (15.97 km) |
| San Marcos to Oceanside (New York) | 2,435.56 mi (3,919.66 km) |
| San Marcos to Ocoee (Florida) | 2,127.01 mi (3,423.10 km) |
| San Marcos to Oconomowoc (Wisconsin) | 1,693.34 mi (2,725.17 km) |
