By then, it had been discovered that the Columbia River system, which drains into the Pacific, had a similar latitude as the headwaters of the Missouri River, and it was widely believed that a connection or short portage existed between the two.
Para entón, descubriuse que o sistema do río Columbia, que desemboca no Pacífico, tiña unha latitude similar á das cabeceiras do río Missouri, e críase amplamente que debía de existir entre ambos unha conexión ou curto porteo.