Transportation (IMAGE) National Geographic Society Caption This is an aerial view of Maryland's Interstate 495 during rush hour. Credit ©2009 Sarah Leen / National Geographic Usage Restrictions IMAGE IS FOR YOUR ONE-TIME EXCLUSIVE USE ONLY FOR MEDIA PROMOTION OF NATIONAL GEOGRAPHIC'S GREENDEX. NO SALES, NO TRANSFERS. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.