According to the plan released in March, activities that would cease during a shutdown include air traffic controller hiring, field training for controllers and air traffic performance analysis. Travelers to the country’s national parks could see a big impact, affecting some of the most popular tourist destinations in the US. States have also stepped in to keep some national parks open using their own funds. Colorado also said in 2023 that it would keep its four national parks and other federal lands open. “In the event of a federal shutdown, we are committed to keeping these areas accessible,” the message reads.