Car production involves factors such as entrepreneurship, capital, labor, regulations, market conditions, environmental standards and socio economic circumstances, in USA the automobile industry is the most important sector since the 1920s when mass production lowered the prices and became a cyclical process due to the durability of the average vehicle; so it declined in the early 1930s but several years later, not only the return of men from the war spurred the production but people wanting to replace their old ones for new versions as well, instead of repairing them due to the lower prices.
The South's economy was based mainly on the production of cotton for export. There was very little manufacturing. By contrast, the North's economy had a great deal of manufacturing and relatively less farming.
