Complex sentence: Plant City Union Depot served both the Atlantic Coast Line Railroad and Seaboard Air Line Railroad even after the merger into the Seaboard Coast Line Railroad until passenger service ceased operations in 1971, and has been on the National Register of Historic Places since 1975.
Split into simpler sentences: Plant City Union Depot served both the Atlantic Coast Line Railroad and Seaboard Air Line Railroad even after the merger into the Seaboard Coast Line Railroad until passenger service ceased operations in 1971. The station has been on the National Register of Historic Places since 1975.