As indicated above, the overwhelming majority of the emigrants to the United States through both Bremen and Hamburg between 1850 and 1855 was comprised of German nationals, and of the non-nationals on board these ships most were in fact ethnic Germans. As a consequence, neither a distinction between ethnic Germans and German nationals nor the 80-percent requirement should preclude the publication of the passenger manifest of any ship arriving in the United States from either of these ports during this period. Although GTA should contain the passenger list of every ship from Bremen or Hamburg arriving in the United States at one of the five major ports of entry between 1850 and 1855, it clearly does not.
Additional gaps exist throughout all nine volumes of the work.
For the fourth quarter, during which 17,493 German immigrants arrived at New York, GTA contains the manifests of only two ships, representing 493 German nationals. The reviewer and his colleague, Kevin Tvedt, brought the gap between 19 July and 20 September to the attention of GTA co-editor Filby during his visit to California in September 1988. Upon his return to Baltimore, Mr. Filby discussed this gap further with Daniel C. Helmstadter, President of Scholarly Resources, the publisher of GTA , who contacted Professor Glazier at the Balch Institute Center for Immigration Research. Indeed, for no port do the original ship passenger manifests survive complete. Many were deliberately destroyed by district customs collectors, who had sent copies and abstracts to the Secretary of State and anticipated no further use of them locally.