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Wilmot Proviso
Henry Clay's proposal meant to keep the number of slave states and free states equal.
Free-Soil Party
A failed law meant to ban slavery in areas won during the Mexican-American War.
Popular Soverignty
The idea that the people have the right to create their government.
Missouri Compromise
Founded in Buffalo, the main goal was to keep slavery out of the western territories.

Actually, these are not statements but rather definitions of terms related to the history of the United States. Do you have a specific question or do you want me to explain these terms further?