What economic and political forces fed westward expansion during the 1840s?

Between 1815 and 1860, 5 million European immigrants landed in US.
3 million came between 1845-1854
Irish led the way as the most numerous between 1840-1860
Germans came in close second
Newcomers and Natives
2nd Concept: What Economic and Political forces fed westward expansion during the 1840s?

Why do you have to ask such hard questions.

Idon't think any of em are right, you need to add the number of what paragraph you got your citation from