Positive Train Control (PTC) is a safety feature on railroads in the United States. It was first signed into law by former President George W. Bush on October 16, 2008 as a result of the Chatsworth train collision in Chatsworth, California, near Los Angeles, but final regulations weren't published until January 15, 2010. The original deadline for the PTC system was to have it fully implemented by December 31, 2015, but before that could happen, the Philadelphia train derailment, also known as the Amtrak 188 incident, happened in Philadelphia, Pennsylvania on Amtrak's Northeast Corridor on May 12, 2015, which intimately revealed that railroad companies, including Amtrak, weren't fully on track for the deadline. As a result of this, the PTC deadline was extended to December 31, 2018 from a bill signed by former President Barack Obama on October 29, 2015. The deadline was later extended again to December 31, 2020 when H.R. 3763, the Surface Transportation Reauthorization and Reform Act of 2015, was passed by Congress alongside approval from the Federal Railroad Administration (FRA).
As of December 29, 2020, it is believed that PTC is now fully implemented on all 57,536 required freight and passenger railroad route miles.