Adirondack State Park was created by assembling pieces of state land that was intermixed with public property. Many national parks also have privately-held lands within them called in-holdings. Grand Teton, Acadia, Shenandoah and Great Smoky Mountains National Park are a few that come to mind that were created when private or public individuals purchased land with the sole purpose of setting it aside (John D Rockefeller was well know for doing this on the sly). In some instances, private landholders didn't want to sell their land… for any price. THe government couldn't necessarily use eminent domain to obtain the land and it remained in the owner's hands.