Your state's library and archives provide information about phonebooks from the 1980s or before. The phonebooks are gathered across the state and serve as a proof of location and time for people and businesses in a particular area or town.
Most states, including Wyoming and Tennessee, provide an online catalog-style database that indicates the telephone directory's available years and its primary community or town of origin. Before paying a visit to the nearest state library, check the library's website first, if applicable, to see if it holds a phonebook from 1980. The Library of Congress Local History and Genealogy Reference Services also saves U.S. telephone directories from 1976 to 1995 on microfiche.