Free parking

On Saturday, U.S. national parks and federal recreational areas are throwing a party for National Public Lands Day, and you’ll be able to visit them for free, participate in special ranger-led outdoor activities and volunteer -- jobs like yanking out invasive plants, improving wildlife habitats, beautifying hiking trails, planting trees and more -- across the country. Anyone who volunteers at Grand Canyon National Park (above) that day will receive a free one-day pass for future use at any national park site (worth up to $25 at such places as Yellowstone or $20 at Yosemite and Sequoia & Kings Canyon). Info: National Public Lands Day, (202) 261-6462, www.publiclandsday.org.