San Diego was not affected by the great depression as much as other metropolitan areas that relied on heavy industry, patronage declines were just as much of an economic problem to the company. Much of its patronage was leaving in favor of personal automobiles rather than the outdated and uncountable streetcars, many of which were built prior to World War One.
The SDERy ordered 28 PCC cars from the St. Louis Car Co. on July 18, 1936 to replace aging equipment, modernize its system, and bring back passengers. SDERy was among the first streetcar systems in the United States to purchase the streamlined PCC car. These new cars were given numbers, 501-528. The 502 arrived in San Diego on March 17, 1937 was parked at the north curb of Horton Plaza on that day till March 29th so that it could be viewed by city citizens.
During World War II, pationage increased 340% putting many of the older cars back into service. Several retired cars from New York’s Third Avenue Railway were even transplanted to the SDERy (1043 is a surviving example of this at the museum). The 502 was one of two cars painted red and blue for the American Red Cross's blood donation campaign. In 1948, National City Lines purchased the San Diego Electric Railway, and by 1949 the SDERy closed its streetcar lines in favor of busses. San Diego was the first city in North America to completely abandon PCC streetcar in favor of rubber tired transit coaches.
In 1950, 502 and 16 of its sister PCC cars were sold to El Paso City Lines for service on the international loop between El Paso, Texas, and the Mexican border city of Ciudad Juarez, Chihuahua, where it was numbered 1500. Before leaving San Diego the cars were rebuilt and repainted. The cross seats were replaced with longitudinal seating, so customs officials could check passengers quickly as they cross the border. This line was closed in 1973, and El Paso City Lines shut down a year later. Instead of scrapping the cars, the City of El Paso decided to store them long-term at a closed airfield. The San Diego Electric Railway Association in 1984 purchased the 502 in hopes to restore it for use on the new San Diego Metropolitan light rail line in San Diego. The 502 was stored in the San Diego Trolley yard for some time until MTS staff ordered them to move out. Sometime after moving out, the 502 suffered from an arson fire. After this, SDERA was unable to raise sufficient funds for a full restoration. It was then sold to a private owner in 1998 for a proposed streetcar line in the South Lake Tahoe Area.
In 2020, the museum acquired 502 and is now on display waiting its turn in restoration.