No predictions loaded for 1997. This site serves NOAA predictions from its own store, and this period has not been fetched for Delaware City yet. Nothing is estimated or interpolated in its place. NOAA's own page for the station has the official table: tidesandcurrents.noaa.gov.
tidealmanac.site/us/de/delaware-city-8551762/1997
Delaware City, DE tide table 1997 (printable) · Tide Almanac