San Bernardino County was a participant in Pacific Electric’s Red Car Line, the  privately owned mass transit system in Southern California that emanated from Los Angeles consisting of electrically powered streetcars, light rail that existed between 1901 and 1961. Ultimately, organized around the city centers of Los Angeles and San Bernardino, by the 1920s it was the largest electric railway system in the world.
Electric trolleys first traveled in Los Angeles in 1887. In 1901, the Pacific Electric Railroad was by railroad executive Henry Huntington and banker Isaias W. Hellman after they had success developing a trolley system in San Francisco. Together, Huntington and Hellman purchased some existing rail lines in downtown Los Angeles, which they standardizes and organizes into one network called under the Los Angeles Railway.
They tasked engineer Epes Randolph to survey and lay out the company’s first lines which would be to Long Beach. The line to Long Beach opened for business in July 1902.
The enterprise involved not only passenger transportation but carrying of freight as well as supplying electric power to the communities along which the lines extended. Huntington and Hellman and their investors picked up large chunks of real estate along the way. A flling out between Huntington and Hellman occurred as the result of  Huntington’s insistence on reinvesting profits into costly expansion rather than paying any stockholder dividends. Consequently, the Hellman investment group sold their share of the company to E.H. Harriman, essentially trading Harriman’s Wells Fargo Bank to Hellman for his railroad holdings.
As partners Huntington and Harrington cooperated with regard to the Red Car venture but were wary of one another because Harrington did not want the line to interfere with his Southern Pacific line operations. In 1906, Moses Sherman sold his Los Angeles Pacific Railroad and the Pacific Electric picked up lines to Pasadena, San Fernando Valley and West LA.
Huntington sold out all his Pacific Electric stock to Harriman and in 1911 what was called the “Great Merger” took place as the Southern Pacific and Pacific Electric became a single operation, with all electrical operations now under the Pacific Electric name.
Shortly thereafter the Red Car line expanded eastward to Monrovia, Azusa, Pomona, Cucamonga Etiwanda, Fontana, Colton and Redlands, making the Pacific Electric the largest operator of interurban electric railway passenger service in the world, with 2,160 daily trains over 1,000 miles of track.
In the late 1930s that the influential Automobile Club of Southern California engineered an elaborate plan to create an elevated freeway-type “Motorway System,” a key aspect of which was the dismantling of the streetcar lines, replacing them with buses that could run on both local streets and on the new express roads.
When the freeway system was planned in the 1930s the city planners planned to include light rail tracks in the center margin of each freeway but the plan was never implemented.
The Whittier and Fullerton was cut in 1938, Redondo Beach, Newport Beach, Sawtelle via San Vicente, and Riverside in 1940. When the San Bernardino Freeway opened in 1941 but was not yet connected to the Hollywood Freeway, while the “Four Way” overpass was being constructed, westbound car traffic from the SB freeway poured onto downtown streets near the present Union Station. PE’s multiple car trains coming and going from Pasadena, Sierra Madre, and Monrovia/Glendora used those same streets the final few miles to the 6th and Main PE terminal and were totally bogged down within this jammed traffic. Schedules could not be met, plus former patrons were now driving. The San Bernardino line, Pomona branch, Temple City branch via Alhambra’s Main St., San Bernardino’s Mountain View local to 34th St., Santa Monica Blvd. via Beverly Hills, and all remaining Pasadena local service were all cut in 1941.
The last vestige of the Red Car system into San Bernardino County was the  interurban Railroad post office service operated by Pacific Electric on its San Bernardino Line. This was inaugurated comparatively late, on September 2, 1947. It left LA’s Union Station interurban yard on the west side of the terminal turning north onto Alameda Street at 12:45 pm and San Bernardino at 4:40 pm, taking three hours for the trip. It did not operate on Sundays or holidays. This last Rrailroad post office was pulled off May 6, 1950.