Tower 16 stood in Sherman, Texas, at the junction of two railroad tracks, where it controlled which train had the right of way and which had to stop. It served as the control tower for an interlocking plant at the grade crossing of the Southern Pacific-Frisco Railroad running north and south and the Texas & Pacific running east and west. Authorized for operation by the Railroad Commission of Texas on July 18, 1903, and likely operating before that official date, it worked for nearly 100 years before being retired from service on October 23, 2001, after a new automated system was installed. Using signal lights, a blocking control bed, and a bank of metal handles, the tower gave red and green signals to govern train movements through the crossing, while control operators staffed the tower, communicated with trains, and managed traffic through the interlocker and along a segment of track to the next junction. Tower 16 protected the crossing of the Texas & Pacific line from Sherman to Texarkana, the Houston & Texas Central from Dallas to Denison, and the St. Louis, San Francisco & Texas from Denison to Irving. At its closure, it controlled the BNSF line from the south side of the Red River bridge north of Denison to the South Sherman Junction. It was the last working interlocking tower in North Texas, and after federal approval was given to retire the signal system and the crossing diamond in Sherman was removed, it was saved from destruction and moved to Grapevine, where it stands with other historic railroad structures and equipment as part of educational efforts preserving North Texas railroad history.