A man walks his bike up a pedestrian ramp on the "Day Without Cars" in Bogota, Thursday, Feb. 4, 2010. Bogota has a population of 8 million people and over a million cars. Public transportation and motorcycles are permitted on the "Day without cars." AP Photo logo AP Photo 24 months ago

A man walks his bike up a pedestrian ramp on the "Day Without Cars" in Bogota, Thursday, Feb. 4, 2010. Bogota has a population of 8 million people and over a million cars. Public transportation and motorcycles are permitted on the "Day without cars."