How did early Americans know that manifest destiny would lead to the Pacific Ocean?

by Minkovich

They always envisioned that the country would spread from coast to coast, from sea to shining sea. Okay, but how did they know that, if they traveled west far enough, they would eventually come across water and not just infinite land? Because for them to know where the Pacific Ocean begins, that would imply that they've already gone through and settled that land. How did they know about the Western United States and the Pacific Ocean without first claiming all that land?

CatholicRealist

TL;DR: The timeline of your question is out of order a little. Manifest Destiny was a mid 1800s American idea and there were some maps by then showing the western ocean.

There were halfway decent maps of North America available well before the Manifest Destiny movement so there was no unsolvable mystery at that time as to the extent of the western lands. The Lewis and Clark expedition departed in 1804, at that time those guys went from Missouri all the way to the Pacific Ocean in what is now Washington state. Their expedition was completed round trip to St Louis in 1806. They made lots of maps and others followed in their footsteps to a certain extent. I'm on mobile but I have sources I could get to If needs be. If I remember my college classes properly Manifest Destiny didn't pick up steam as an idea till after 1850.

Searocksandtrees

Hi, it might be worth looking into European explorers who had been mapping the Pacific coastline of North America, others searching for various routes around or through the Americas (e.g. the NorthWest Passage, the Lewis & Clark expedition), the extent of the fur trade (e.g. the Russian-America Company, Hudson's Bay Company, North West Company), and settlements that had already been established on the Pacific. Here are a smattering of earlier posts on some of this to get you started: