Part I: National Parks - Central California's National Parks are known worldwide and attract millions of visitors each year. In 2010, over 4 million people visited Yosemite National Park, just short of breaking the park's all-time record. But those visitors bring big city problems with them, from traffic jams, to pollution and safety concerns. This week on Quality of Life, we examine the difficult task of balancing public access with preservation of natural resources, in Yosemite and beyond.