It's Free Park Week. The National Parks are free this week. More than 300 National Park Service sites are offering free admission. Some of the nation's most popular National Parks are included, such as Yellowstone,  Yosemite, and Rocky Moutain National Park. Officials in Colorado say visitors will be able to ski in the  higher elevations, or hike the lower ones. If you can't make it to a National Park this week, there's another 'freebie' coming June 21st.