In the 1800s, what route did pioneers follow to settle the pacific coast?
the mississippi river

In the 1800s, what route did pioneers follow to settle the Pacific Coast?

the Mississippi River

Explanation:

The route of Oregon was one of the main routes of migration by earth of North America, that left from several places in the Missouri river and arrived until the Territory of Oregon, then in most of the rivers of the basin of the Mississippi and the Missouri.

The first to use the route were, by 1820, the fur traders, followed by missionaries, military expeditions and some groups of civilians from the 1830s.

The answer is: The Oregon Trail.