"In 1934, when water companies declared acres of unspoiled forested hillsides surrounding San Francisco Bay "surplus" — and thus available for development — citizens banded together to urge creation of the East Bay Regional Park District. Despite the Depression, public funds were secured to purchase and permanently protect this land. Today it has become America's largest urban park district, encompassing 98,000 acres of open space and natural areas."
It goes on to argue that the precedent set in the Great Depression, when the newly formed Civilian Conservation Corps (CCC) constructed fire roads, planted trees, and built trails and buildings in our parks, is a model for the win-win combination of conservation and economic revitalization.
Reading the blog post prompted me to do a little reading: for a history of the East Bay Regional Parks District (EBRPD) try this brief San Francisco Chronicle article or the more lengthy EBRPD timeline. I like this Flickr pool of historical park photos.