I love discovering names in unique documents, and I've seen plenty of souvenir passenger lists, but none like these from the Panama Mail Steamship Company. They're tri-fold postcards that I suppose a passenger would mail to family or friends (?). Souvenir passenger lists are not a substitute for the actual ship manifest, but they are a pretty good indicator that the ancestor did travel on the ship; or at least they purchased a ticket.
These postcards list the passenger names along with their destination, some of which include Mazatlan, San Jose de Guatemala, Acajutla, Havana and New York. On the cards I've seen less than half of the passengers make the full cross-coastal trip. The names/titles of the officers are also listed.
This shipping company was formerly called the Pacific Mail Steamship Company, established 1848. The 1922 postcard listed below uses this name, the others have the Panama name, but formatting and marketing text on backside is exactly the same. "Operating the steamers Columbia, Ecuador, Venezuela and Santa Ana, between San Francisco, Los Angeles Harbor, New York through the Panama Canal."
Here are the four cards that I recently purchased: