The transportation revolution had several important effects on the antebellum
political equilibrium. First, it caused western and southern political views to
differ by bringing more easterners and European immigrants into the West.
Second, it reduced the costs of rerouting western exports to the non-South,
which decreased the expected costs to the West of conflict with the South.
Third, it greatly increased western population, which brought more free states
into the Union and changed the balance in the Senate. Fourth, it increased
northern numerical superiority over the South, giving the North a major
advantage if an armed conflict did occur. These changes led the West to ally
with the East and caused the South to secede.