Southeastern Pennsylvania Transportation Authority (SEPTA) operates a 25 Hz traction power system in the vicinity of Philadelphia, Pennsylvania, that it inherited from the Reading Railroad. This system is separate from but similar to the system designed by the Pennsylvania Railroad, which is now operated by Amtrak. SEPTA's trains can run over either system because the voltage and frequency presented to the locomotive are essentially identical. However, the ex-Reading system is not electrically connected to the ex-PRR system.