Answer: majority vote by the people living there (states' legislatures).
Explanation:
"Popular" means a vote by the populace, the people (or through their representatives in legislatures).
"Sovereignty" refers to where power or authority lies.
So "popular sovereignty" means that the people of the states had authority over their own territory's approach to the slavery issue.
The Civil War was fought over both the issue of "states' rights" (the idea of each state's popular sovereignty), as well as the issue of slavery, which was ended in the United States after the Civil War. From that point on, at least on the issue of slavery, states could not decide their own path. The 13th Amendment was added to the US Constitution and made slavery illegal in all states.
Here's what the 13th Amendment said:
- <em>Section 1. Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
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Section 2. Congress shall have power to enforce this article by appropriate legislation</em>
