The Panama Pacific Line was a subsidiary line of International Mercantile Marine (IMM) established to carry passengers and freight between the U.S. East and West Coasts via the Panama Canal.[1]
Although IMM had begun preparations for this intercoastal service as far back as 1911,[2] service began in May 1915 with the former Red Star Line (another IMM subsidiary line) ships Kroonland and Finland.[1][3] When landslides in September 1915 closed the canal for an extended time, Kroonland and Finland were reassigned to the IMM's American Line.[4] The outbreak of World War I and its strain on international shipping caused the intercoastal route to be abandoned.
In 1923, Kroonland and Finland were returned to the resurrected intercoastal route along with the American Line passenger steamer SS Manchuria.[5][6] Manchuria's sister ship Mongolia supplanted Kroonland on the route in 1925.[7]
Three ships featuring steam turbines and electric drive—California, Pennsylvania, and Virginia—came into service beginning in 1928, replacing all of the other ships on the intercoastal service. These three newest ships featured a drive-on service for passengers' automobiles, which allowed passengers to disembark with their car at ports of call, like Havana, a stop added in the early 1930s.
In 1936, California, docked at San Pedro, California, was the setting for the SS California strike, which contributed to the demise of the International Seamen's Union and the creation of the National Maritime Union.
By 1938, the intercoastal service had ended and the three electric ships, California, Pennsylvania, and Virginia were sold for use on South American routes.