While your car's tires may have intimate familiarity with the roads, most likely you ride atop them without much thought beyond how they'll get you from point A to point B. Besides providing you with a path around town, roadways enable efficient commerce. In fact, the United States so loves roads that it's built almost 4 million miles (6.4 million kilometers) of them, according to the U.S. Geological Survey.
There is, however, increasing concern about roads' impact on the environment. How harsh are roads on their ecological surroundings?