16 U.S.C. § 410vv–6

In acquiring land within the historic zone, the Secretary may permit an owner of improved residential property within the boundaries of the historic zone to retain a right of use and occupancy of such property for noncommercial residential purposes for a term not to exceed 25 years or a term ending at the death of the owner, or the owner’s spouse, whichever occurs last. The owner shall elect the term to be reserved.