America's most famous landmarks are the 51 national parks that have made the nation's park system the envy of the world.
However, these crown jewels are but part of a system now bulging with 367 units.
Besides the glory parks, there are more than a dozen other categories, including national monuments, battlefields, preserves, seashores and historic sites. There are also 18 national recreation areas, including the one in the Santa Monica Mountains.
The recreation areas are mainly of two types. Some were established around reservoirs created for water supply and hydroelectric production. No longer natural settings, these sites still offered recreational opportunity and attractive scenery.
Then a new breed of national recreation areas emerged in the 1970s to preserve wild lands near cities and make the outdoors more accessible to urban America.
Egalitarian and political impulses both played a part. The new parks provided a means to serve the growing cities, and to cultivate urban lawmakers whose support the park system badly needed.
Although a bane of environmentalists through much of his political career, Walter Hickel, current governor of Alaska, was a champion of the urban recreation areas while interior secretary during the Nixon Administration.
Recreation areas established by Congress in the 1970s included the Golden Gate National Recreation Area in the Bay Area, Gateway National Recreation Area in New York and New Jersey, the Cuyahoga Valley National Recreation Area near Cleveland, and the Chattahoochee River National Recreation Area in Atlanta.
The Santa Monica Mountains National Recreation Area joined the ranks of the new urban parks in 1978.
Its mission was to link existing islands of parkland to form a continuous swath of habitat and public open space across the Santa Monica Mountains.
In pushing for public acquisition, local supporters had the additional motive of curbing development in an area that, as recent events have shown, is extremely prone to wildfires.