In many respects, your question is like one already posted here, How can I determine what records are available in a particular locale? The same principles apply for discovering records for a particular time or topic.
My checklist for finding new record groups looks like this:
- Learn what records might have been created in a particular time and place.
- Research which of those records might still exist.
- Research what repositories might hold those records.
- Research which online repositories might hold those records.
As part of my step one, it often helps to ask why records are created. Many of the lists of passengers inbound to the USA that we are familiar with were created as a result of Federal laws that were created in 1882. If you look at the headers of the passenger lists, you can see how the questions changed over time, and what information the federal government was interested in collecting about people coming into the United States.
There are far fewer records of people departing. Records won't be created unless there is some compelling interest to do so. Most of these records won't help you because they are too early or too late for your question, and none of them are from San Francisco, but I'm including them in this answer to show examples of what records were created, and so you and other readers can see the explanations about why they were created. So far I have discovered:
NARA Microfilm Publication A3376, Passenger Lists of Vessels (January 1949-March 1957) and Passenger and Crew Lists of Airplanes (June 1947-March 1957) Departing from Seattle and
Tacoma, Washington. There is a downloadable pdf describing this collection.
The Aliens’ Applications for Permission to Depart from the United States (ARC ID 567234). See the National Archives' blog NARAtions NARA Coast to Coast: Emigration Records at the National Archives at Philadelphia, Part 1 for a description of these records, which were from the WWI era. (The second part of this article, which was to talk about Outward Bound Alien Passenger Lists, was apparently never written; in a post a few weeks later, the author said "I know I promised to post Part 2 about Emigration Records at the National Archives at Philadelphia as the next NARA Coast to Coast post, but I’ve gotten a bit stuck in my research and other work has gotten in the way." and the author only has one other post after that on the blog.)
These are not travel records, and they are also outside your period of interest, but other records created about non-citizens in the United States include:
Alien files (A-Files), files created by the Immigration and Naturalization Service (INS) beginning in 1944, about aliens (non-citizens) residing in the United States. These files are being transferred from the INS to the custody of the National Archives in five-year blocks, 100 years after the alien's year of birth. See the page Alien Files ("A-Files") at the National Archives at San Francisco for more details.
Aliens were also required to register during the WWI period, and a blog post from NARA's Prologue Magazine, Enemy Aliens in Kansas City describes those records.
If you were expecting outbound passenger lists comparable to the incoming ones, except for the ones from Washington state mentioned above, there may not be any. The San Francisco Maritime Museum's page, in their Frequently Asked Questions, says:
We have some passenger lists (the majority are at the National Archives). If you
know the name of the ship and the date of the voyage
you are interested in, you can contact us to see if we have any
resources about the passengers.
The majority of passenger lists for arrivals in the West Coast are at the National
Archives in San Bruno, which has made available an
Adobe Acrobat .pdf file describing which ship's lists are held in
Record Group 85, Records of the Immigration and Naturalization
Service. (More detailed information on passenger lists at the National
Archives is also available.) Please note that the records are for
arrivals only, not departures, as records for departures were not
The San Bruno office referred to is the National Archives at San Francisco which is located in San Bruno, California. They might be able to advise you about other useful San Francisco-area records that I don't know about.
One possible (informal) source of information about passenger departures or ship departures might be historical newspapers. Passengers might be listed by name in the social news columns; ship departures (without passenger information) might also be listed in shipping news sections. For any online vendor (especially those which require a subscription), check to see what newspapers are in the collection and what years are covered, as coverage can be very spotty.
- The California Digital Newspaper Collection is a project of the Center for Bibliographical Studies and Research (CBSR) at the University of California, Riverside. This freely-accessible collection contains 71,625 issues comprising 595,046 pages and 6,837,378 articles.
- other newspaper resources are summarized in this list of Online Genealogy Databases from the website SFGenealogy
If your relatives passed through a port in the United Kingdom, they might be in the records found in the National Archives there:
You can search to see who might be mentioned in the collections without signing up for the service. FindMyPast reveals more information to unsubscribed users about the search results than Ancestry does, but you can see how many possible matches might be in the collections, if any. You can also read the "about the collection" descriptions to learn more about what information might be contained in the records. To view the original records, FindMyPast offers both pay-per-view options and subscriptions; Ancestry only has subscriptions. Both services allow users to register for free, and allow some limited features to registered (unpaid) users. Learning more about the collections and trying some searches first will give you a better idea of whether it might be worthwhile to subscribe or pay to view records.
The Gjenvick-Gjønvik Archives, whose major focus is on ships departing Europe for the Eastern coast of the United states, has a list of Major European ports. Presumably shipping lines which had ships departing from these ports for the US would also have the ships calling there on the return voyages. (Unfortunately he doesn't have information about ship companies serving San Francisco.) If you look at the headers of the manifests for the incoming passengers, you can see which companies were sailing in and out of San Francisco and which ports they used.
I don't know what records might have been created by Germany or Czechoslovakia, and what records (if any) might have survived. Here are the articles from the Family Search wiki for libraries and archives in those countries:
You could also try searching the FamilySearch catalog to see what records might be available.
Edited to comment on bgwiehle's answer: any records you can find, on any matter whatever, can help in establishing date bounds. I use spreadsheets to make timelines -- putting all the information in order helps me see the sequence more clearly than just writing it out in a document (although that can be useful, too).
I especially like city directories for evidence of residency, taking into account that the listings can 'lag' behind the actual time of residency. There is a 'lead time' between the directory company gathering information and publication; there is a also a 'lag time' where the listing might persist after people have moved.