Answer:
A divided regional identity (with a bit of national unity) developed.
Explanation:
Politics: Some contributed (voting rights) to unity, others (nullification) clearly divided the country.
Economics: Market revolution was a bit of both but Tariffs and the clash between the industrial north and the agricultural south was dividing the country and contributed to a regional identity.
Foreign Policy: The war of 1812 united the country; the westward expansion was uniting and dividing at the same time.
As we take in account that Economics is always the most important thing for the general public, the regional identity grew more than the national unity did.
Cars became popular in 20th century. I think this is the right answer.
The Vietnam war made congress decide <span />
