Federal Enclave

In United States law, a "federal enclave" is a parcel of federal property within a state that is under the "Special Maritime and Territorial Jurisdiction of the United States." As of 1960, the latest comprehensive inquiry, only seven percent of federal property had enclave status, of which four percent (almost all in Alaska and Hawaii) was under "concurrent" state jurisdiction. The remaining three percent, on which some State laws do not apply, is scattered almost at random throughout the United States. In 1960, there were about 5,000 enclaves, with about one million people living on them. These numbers would undoubtedly be lower today because many of these areas were military bases that have been closed and transferred out of federal ownership.

Since late 1950s, it has been an official federal policy that the states should have full concurrent jurisdiction on all federal enclaves, an approach endorsed by legal experts.