The United States is one of the world's largest countries based on the area with a total of 3,794,100 square miles (9,826,675 sq km) spread out over 50 different states. Much of this land is developed into large cities or urban areas like Los Angeles, California, and Chicago, Illinois, but a large portion of it is protected from development via national parks and other federally protected areas that are monitored by the National Park Service that was created in 1916 by the Organic Act. The first national parks to be founded in the U.S. were Yellowstone (1872) followed by Yosemite and Sequoia (1890).

In total, the U.S. has almost 400 different nationally protected areas today that range from large national parks to smaller national historic sites, monuments and seashores. The following is a list of the 20 largest national parks out of the 55 in the U.S. For reference their locations and date of founding have also been included.

Largest National Parks in the United States

1) Wrangell-St. Elias

• Area: 13,005 square miles (33,683 sq km)

• Location: Alaska

• Year of Formation: 1980