Why was the Northwest passage thought to be so important?

Prior to the construction of the Panama Canal, the only water route to the Pacific was "around the horn" and along the coasts of South America. Besides being very long, it was very dangerous. It was hoped that a way could be found going northwest that would be shorter, safer, and faster. Lacking such a route, the transcontinental railroad was completed in 1869 and the Panama Canal was completed in 1914. Route 66, the interstate highway that ran from Chicago to Los Angeles, was established in 1926. Had a water route, a "Northwest Passage" existed, these other projects might not have been undertaken until much later.