A rapid growth in the number of visitors has been observed for many national parks in the United States, examples include Yellowstone National Park, Yosemite National Park, Rocky Mountain National Park and Arches National Park. As a result, public transit and parking resources have been stretched closer and closer to their capacities in these parks. In response, some National Park Services (NPS) have started to implement crowd control measurements, such as the timed entry reservation systems, where visitors have to reserve their slots to visit the park during certain time periods of the year. However, such policy does not touch on the fundamental issue of the subject, that is, the carrying capacity of the park. In this paper, we demonstrate that there will be even greater growth in the number of visitors in the near future, which means that a capacity boost is inevitable. Fortunately, we also observe that if we can fix some key bottlenecks, then we can dramatically increase the capacity of the park without destroying more natural land.