The people heading west called themselves emigrants, but we call them PIONEERS.
The American pioneers are any of the people who during the History of the United States emigrated from the settlements of the East Coast towards the settlements of the West Coast and colonized new areas.
The term refers especially to those who were going to populate any territory that had not previously been populated or cultivated by the descendants of European or American society, even though the territory may have been inhabited or used by indigenous peoples.