The National Register of Historic Places is the Unite States government's official list of districts, sites, buildings, structures, and objects worthy of preservation, each of which is known as a Registered Historic Place. The passing of the National Historic Preservation Act (NHPA) in 1966 established the National Register and the process for adding properties to it. Of the more than one million properties on the National Register, 80,000 are listed individually. The remainder are contributing members within historic districts. Each year approximately 30,000 properties are added to the National Register as part of districts or through individual listings.