Answer:
The period from the end of World War II to the early 1970s was one of the greatest eras of economic expansion in world history. In the US, Gross Domestic Product increased from $228 billion in 1945 to just under $1.7 trillion in 1975. By 1975, the US economy represented some 35% of the entire world industrial output, and the US economy was over 3 times larger than that of Japan, the next largest economy. The expansion was interrupted in the United States by five recessions.
$200 billion in war bonds matured, and the G.I. Bill financed a well-educated work force. The middle class swelled, as did GDP and productivity. The US underwent its own golden age of economic growth. This growth was distributed fairly evenly across the economic classes, which some attribute to the strength of labor unions in this period—labor union membership peaked during the 1950s. Much of the growth came from the movement of low-income farm workers into better-paying jobs in the towns and cities—a process largely completed by 1960.
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American Society Of Civil Engineers
It is very much hard to answer.
It was mainly because of how the North and the South of America had different lifestyles and economy's. You would be surprised to know that the Democratic party back then supported Slavery and the republicans dint support Slavery.
Plain Answer: Because of Slavery, Way of Life and Different Economy. The Democratic Party would do anything to keep themselves supported.
West Africa to the West Indies(North America)