It had a brief existence of only sixteen months and was supplanted by the transcontinental telegraph. yet it was of the greatest importance in binding the east and west together at a time when overland travel was slow and cumbersome, and when a great national crisis made the rapid communication of news between these sections an imperative necessity. which of the following best summarizes the main message of these lines? the pony express was invaluable during the national crisis the pony express was all that was available during the national crisis the transcontinental telegraph replaced the pony express (i think this is right) the transcontinental telegraph would have been more effective (doubt this is right)