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In page Pacific Electric:

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PE operated frequent freight trains under electric power throughout its service area (as far as 65 miles [105 km]) to Redlands, including operating electrically powered Railway Post Office routes, one of the few U.S. interurbans to do so. This provided important revenue. The PE was responsible for an innovation in grade crossing safety: the automatic electromechanical grade crossing signal, nicknamed the wigwag.[5] This device was quickly adopted by other railroads. A few wigwags continue in operation as of 2006.[citation needed]