| A | B |
|---|
| contiguous | joined together inside a common boundary |
| urban | densely populated |
| megalopolis | super city made up of connected urban areas |
| rural | sparsely populated |
| coral reef | submerged or low lying structure made of skeletons of sea creatures |
| Appalachian Mountains | oldest mountains in the US |
| Mississippi River | longest river in the US |
| Great Lakes | largest group of freshwater lakes in the world |
| Great Plains | broad, high plains of central US |
| Rocky Mountains | largest mountain range in North America |
| Sierra Nevada Mountains | high mountains found in California |
| Hawaiian Islands | volcanic islands in the central Pacific Ocean |
| free enterprise | people own and run businesses with little government interference |
| service industry | businesses that do not produce a product such as banking, insurance, etc. |
| farm belt | refers to the Midwest where many farm products are produced |
| acid rain | air pollution mixes with water vapor and falls to earth |
| immigrant | people who come to live in a country |
| colony | overseas settlement tied to a parent country |
| revolution | sudden political change |
| republic | people elect their own officials |
| ethnic group | group of people who share a common culture |
| mobile | move often from place to place |
| national park | land set aside to protect wilderness and wildlife |
| Sunbelt | the southern and southwestern states where a mild climate prevails |
| navigable | waterway that is wide and deep enough to allow the passage of ships |
| landfill | area where trash companies dump waste |
| secede | withdraw from the national government |
| suburb | smaller community near a large city |
