The Wilmot Proviso
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It sounds like the Missouri Compromise, where slavery would be permitted 'not north' of Missouri's Southern border.
Right.
In 1820, politicians debated the question of whether slavery would be legal in the western territories. The Missouri Compromise permitted slavery in the new state of Missouri and the Arkansas Territory but it was barred everywhere west and north of Missouri.
Slavery would not be allowed in any territory acqired from the Republic of Mexico.
The document that said slavery was not permitted in any area won from Mexico was known as the Wilmot Proviso.
Slavery would have been permitted in these territories. (Don't know if it happened.)
Slavery was not permitted in the Ohio territory. The Northwest Ordinance of 1787, which established the Northwest Territory, including what would become Ohio, prohibited slavery in the region.
They were concerned that slavery would come 2 kansas
They would have been, if Congress had not appeased them with a couple more states where slavery would be permitted, plus enforcement of the Fugitive Slave Act.
Popular Sovereignty
popular sovereignty
Native Americans were enslaved to some degree.
It was the Wilmot Proviso that said any lands acquired from Mexico would not allow slavery. It was written by David Wilmot, who served as a U.S. Senator from Pennsylvania.
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The Emancipation Proclamation, was the document by President Lincoln, that would bring slavery to an end. Amendment 13, of the Constitution of the United States, forever forbids slavery.
Slavery is a nasty thing. Mexico's father of independence Miguel Hidalgo abolished it at the beginning of the struggle for Mexican independence (1810) but it was never officially put in any legal document until 1829; on 1830 it was approved by the Mexican congress and became a law throughout Mexico and its territories.