North American interlocking towers

A key to symbols is available.


The original version of this list of active North American railroad interlocking towers and cabins was originally compiled for the “Tower Tribute” section in the April 1995 issue of TRAINS magazine by then-Senior Editor J. David Ingles, with help from the following people:

Jerry Angier, John Arbuckle, Byron Babbish, Mike Blaszak, C. S. Burgess, Terry Chicwak, B. B. Cyrus, Dale DeVene Jr., Jim Ehernberger, Lee Gregory, Norm Herbert, S. R. Johnson, Lyle Key, Chris Knapton, Blair Kooistra, John Krattinger, Jim Latimer, John Lucas, Paul Meyer, Dan Munson, David Oroszi, D. G. Orr, R. D. Owens, Mike Palmieri, David Patch, E. G. Peterson, Louis Saillard, Bill Schafer, Dick Schmeling, Lou Schmitz, Joe Slauser, Frank Tatnall, George Werner, and Pete White.

The assistance of these people is gratefully acknowledged.

About these tower listings

Each list is organized alphabetically by state, with regional subgroupings as needed. In most cases, the railroad controlling (and staffing) each tower is named first within the list of railroads involved in the plant.

A total of active interlockings follows the state or group heading. Recent closures are highlighted.

Additions and corrections to this list are welcome. We'd be glad to hear about omissions and would appreciate learning about tower closings so we can update this list.

Additional details (e. g., type and size of control machine(s) and historical or operational data) are welcome.

Corrections and updates may be sent via email.


Entries included must meet the following criteria:

  • The facility must be a locally-controlled interlocking or block station, which excludes most dispatching offices. However, the list does include many facilities that control some remote locations in addition to the locally-controlled interlocking or block station.
  • This interlocking or block station should be operated from a structure primarily devoted to this purpose. Buildings of more than one story are listed as towers; one-story free-standing buildings are listed as cabins. Interlockings or block stations located in a depot, yard office or similar facility are listed as offices. Yard facilities (such as hump towers) are listed only if the facility also controls main line switches and signals.
  • A tower or cabin whose only function is to control movable bridges is included only if the facility controls signals (and possibly switches and derails). A number of movable bridges are locally manned but are interlocked with signals controlled remotely (i. e., by a dispatcher). The personnel staffing these bridges are generally considered bridgetenders and not operators. These facilities are not included.

Key to symbols

Machine type symbols:
E Electric (typically GRS model machine).
EM Electro-mechanical. This type of machine has a mechanical frame with separate electrical levers that are either electrically or mechanically interlocked with mechanical frame.
EP Electro-pneumatic (typically US&S model machine).
M Mechanical frame (old “armstrong” or “strong-arm” levers). The presence of pipeline-operated switches, derails, or signals is indicated when known.
R All-relay machine. Includes CTC- and “NX” or “UR”-style panels, as well as other more modern variants that lack mechanical locking.
Structure type symbols:
B Movable bridge cabin, on or next to bridge.
C Cabin (one-story free-standing building).
O Office (e. g., yard office or depot building).
T Tower (building with two or more stories)