How did westward expansion divide Democrats and Whigs? 1)Democrats favored expansion in order to increase their power in Congress and expand slavery; Whigs opposed expansion because they feared losing power in Congress.

2)Whigs favored expansion in order to reach California and trade in the Pacific;

3)Democrats opposed expansion because they only wanted to sell cotton on the Atlantic.

4)Democrats favored expansion in order to make an alliance with Mexico; Whigs opposed expansion and a Mexican alliance because they believed they were too different culturally. Whigs favored expansion because they wanted to build a railroad from the East to the West; Democrats opposed expansion because they believed sea trade was most beneficial.