How to buy tickets for tourist attractions in the western United States?

The scenic spots in the western United States include New Orleans, Denver, Yellowstone National Park, San Francisco, Las Vegas, Grand Canyon, Yosemite National Park, Disney, San Diego, Lake Powell, Lake Tahoe, Bryce Canyon Park, Grand Teton Park, Napa Wine Country, Presidential Mountain Park, Arch Park, Salt Lake City and Universal Studios. Because air tickets sometimes change, we booked a semi-free trip to the western United States in Zhongxin Travel last year. The main places to visit are Disney and two national parks, Las Vegas and Universal Studios. If you want to go to a theme park, such as Universal Studios, Disney can book tickets online in advance, just print out the reservation page and exchange tickets directly at the door. Each ticket for the National Park is about 15-25 yuan/car. There is no need to buy it in advance. You can count yourself as going to several national parks. If there are a large number of people, you can buy annual tickets at the entrance of the national park, and you can buy 80 yuan/car at every entrance.