Population: 953,207
It's nice to know the biggest city in American paradise has air quality to match its beauty.
Isolated in the middle of the Pacific Ocean, there's almost no pollution blowing in from other places. Homegrown smog doesn't last long either, with the steady trade winds that blow here.
Also helping to clean the air: fairly regular rainfall. Even though Honolulu receives an average of less than 20 inches of precipitation a year, it gets frequent light rains, which flush pollutants from the skies.
The city is also making efforts to reduce auto emissions, according to Mayor Peter Carlisle. "We have an award-winning public transportation system, which includes hybrid vehicles powered partly by electricity," he said. "And we're building a modern new rail system to help further reduce dependency on fossil fuels."
NEXT: Port St. Lucie, Fla.
