In 1901 , the company was sold once more to the " Baltimore Syndicate " , a group of East Coast investors looking to purchase a number of Bay Area railways . In 1902 , these companies all merged to form the United Railroads of San Francisco ( URR ) . The URR then quickly built out the line to San Mateo which was operational on 31 December 1902 . Nineteen new motor cars , numbered 1225 to 1244 went into service on the new line on 7 September 1903 . As URR struggled to rebuild after the 1906 San Francisco earthquake , a shortage of motor cars resulted from conversion of former cable car lines to electric power . The Philadelphia and Western Railroad had ordered twelve motor cars from the Saint Louis Car Company ; but these cars were sold to URR when the original purchaser could n't pay for them . These cars were promptly put into service on the San Mateo line where they became known as '' the Big Subs '' . Their size became a problem as the streets they used became congested with automobiles , and they required too much power on hills . '' The Big Subs '' were retired in 1923 ; and the cars built in 1903 were modernized with electric heaters and deeply cushioned leather seats to continue service until this route was abandoned
1906 San Francisco earthquake
1906 San Francisco earthquake
San Francisco and San Mateo Electric Railway