In terms of studying that attitude and mentality, it would be helpful to study the journals of someone moving Westward during that time period (mid to late 19th century).
I would say <span>specialization of labor.
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According to the Land Ordinance of 1787, a territory could be admitted to the Union when its population was large enough.
African Americans had just risked their lives in the war and now demanded to not be treated like 2nd class citizens.