Question

one of the biggest pull factors that lured people to west was cheap land.

Answer 1

You also forgot about the GOLD RUSH.

Answer 2

Expelling Forces (from the East):
1. Lack of economic success
2. Ways to make a living changed (increased mechanization greatly affected small shopkeepers and craftspeople)
3. Overcrowding
4. Uncongenial social, political, cultural, and/or religious atmosphere
5. Belief that processes of urbanization and industrialization were corrupting people and hindering the proper raising of children

Attracting Forces (from the West):
1. Hope for economic improvement
2. Adventure
3. Correspondence with friends and families who had migrated before
4. Abundance and great availability of land

http://www.connerprairie.org/Learn-And-Do/Indiana-History/America-1800-1860/Western-Immigration.aspx