| A | B |
|---|
| Pacific Ocean | used as an early exploration route |
| Atlantic Ocean | highway for early aexplorers, settlers and immigrants |
| Ohio River | known as the gateway to the west |
| Columbia River | explored by Lewis and Clark |
| Rio Grande | forms the border between Texas and Mexico |
| The Great Lakes | where inland port cities grew in the midwest |
| Mississippi and Missouri River | used to transport farm products |
| Colorado River | Explored by the Spanish (Coronado) |
