There have been many attempts to complete the tunnels, but the reasons why the subway was never completed or used for another significant purpose are unclear. In 1936 the city commissioned the Engineers' Club of Cincinnati to produce a report on how to use the unfinished rapid transit property. The report could not find any use for the tunnels other than what they had been designed for. Because the city's needs had changed from twenty years earlier, the report suggested that the subway "should be forgotten". In 1939 the tunnels were researched for possible automobile traffic, but were found to be unsuitable for that use. In 1940 the city sought the advice of several experts to settle once and for all the fate of the subway. The report recommended placing all streetcar and trolley transportation underground (i.e., a subway), but Cincinnati already had too many other expensive public projects underway. In any case, the plan was put on hold yet again when the United States entered World War II in 1941.