The United States has 63 national parks, which are congressionally designated protected areas operated by the National Park Service, an agency of the Department of the Interior. National parks are designated for their natural beauty, unique geological features, diverse ecosystems, and recreational opportunities, typically "because of some outstanding scenic feature or natural phenomena." While legislatively all units of the National Park System are considered equal with the same mission, national parks are generally larger and more of a destination, and hunting and extractive activities are prohibited. National monuments, on the other hand, are also frequently protected for their historical or archaeological significance. Eight national parks (including six in Alaska) are paired with a national preserve, areas with different levels of protection that are administered together but considered separate units and whose areas are not included in the figures below. The 424 units of the National Park System can be broadly referred to as national parks, but most have other formal designations.

Thirty states have national parks, as do the territories of American Samoa and the U.S. Virgin Islands. The state with the most national parks is California with nine, followed by Alaska with eight, Utah with five, and Colorado with four. The largest national park is Wrangell–St. Elias in Alaska: at over 8 million acres (32,375 km2), it is larger than each of the nine smallest states. The next three largest parks are also in Alaska. The smallest park is Gateway Arch National Park, Missouri, at 91 acres (0.37 km2). The total area protected by national parks is approximately 52.2 million acres (211,000 km2), for an average of 829 thousand acres (3,350 km2) but a median of only 208 thousand acres (840 km2).

The national parks set a visitation record in 2017, with more than 84 million visitors and set a further record in 2018 with a 0.1% increase. Great Smoky Mountains National Park in North Carolina and Tennessee has been the most-visited park since 1944, and had over 14 million visitors in 2021. In contrast, only about 7,000 people visited the remote Gates of the Arctic National Park and Preserve in Alaska in 2021.
Based on the paragraph below, which are the most and least popular National Parks in the US?
If we use number of visitors as a proxy for popularity then The Great Smoky Mountains National Park with over 14 million visitors in 2021 would rank as the most popular National Park. The least visited National Park is the Gates of the Arctic National Park and Preserve. Its lower visitation rate may have more to do with its remoteness than the Park's popularity.