State parks are parks or other protected areas of the United States and in Mexico for an area of land preserved on account of its natural beauty, historic interest, recreation, or other reason, and under the administration of the government of a U.S. state or one of the states of Mexico. State parks are protected area of IUCN category II. The term is also used in Australia, though the distinction between state and national parks there is different.

State parks are thus similar to national parks, but under state rather than federal administration. Similarly, local government entities below state level may maintain parks, e.g. regional parks or county parks. In general, state parks are smaller than national parks, with a few exceptions such as the Adirondack Park in New York.

In Australia, both state and national parks are under the administration of state governments, because the first national parks predate the federation of Australia. State parks have a lesser degree of significance and protection (for instance, they are frequently logged).

In the United States, state parks have an older history than national parks. In 1864, when the federal government saw the need to protect the Yosemite Valley and Mariposa Grove, Abraham Lincoln ceded the land to California as a state park. This was because, at the time, preservation of land for the public was seen as a proper role for the states rather than the federal government. Later the state park was incorporated into Yosemite National Park. Perhaps the oldest state park is Georgia's Indian Springs State Park. Since around 1825, Indian Springs has been operated continuously by the state as a public park, although it did not gain the title "State Park" until 1931. In 1893 Pennsylvania operated Valley Forge as a state-owned park. The first state park with the designation of "state park" was Mackinac Island State Park when Mackinac National Park, the nation's second park created in 1875, was transferred from federal control to the State of Michigan in 1895. Many state park systems date to the 1930s, when dozens of state parks across the country were established with assistance from the Civilian Conservation Corps.

Similar systems of local government maintained parks exist in other countries, but the terminology varies. There are approximately 3,675 state parks in the United States.