Common understanding might equate “public lands” with all property owned by various governmental agencies, federal, state and local. As a legal term, “public lands” has had different meanings at various times.
The classic definition of “public lands” included lands of the United States subject to disposition under the general land laws, which would exclude lands in National Parks. The current technical definition of “public lands” is lands and interests in lands managed by the federal Bureau of Land Management (BLM). In contrast to these two legal definitions, the land within the statutory mandate of the Public Land Law Review Commission included not only BLM-managed lands, but National Park Service, Forest Service, and Fish and Wildlife Service lands. This definition approximates the one used in this blog. These are lands to which the public generally is afforded some access and which are managed pursuant to goals established by public processes.
Maps of lands managed by these agencies are available from them.