Dark territory is a term used in the North American railroad industry to describe a section of running track not controlled by signals.
The primary safety concerns with dark territory stems from the lack of any form of direct or indirect train detection along the route.
[2] The total reliance on manual procedures to ensure safety has occasionally resulted in train wrecks, some with fatalities, due to either miscommunication or oversight on the part of operating personnel.
[1] In 1948 the Interstate Commerce Commission set a nationwide speed limit of 60 miles per hour (97 km/h) for trains not protected by some kind of block system (including manual block and track warrants) and in 2012 this was expanded to include all lines considered dark territory.
Since 1991 the National Transportation Safety Board (NTSB) had recommended that railroads be required to install new forms of signaling technology, such as positive train control (PTC), that can stop trains from exceeding their procedural authorities and warn them of improperly lined switches.