1. Antislavery: This position was held by many northerners, particularly in the abolitionist movement and the Republican Party. Antislavery northerners believed that slavery was morally wrong and should be abolished as soon as possible. They supported measures such as the Wilmot Proviso, which would have banned slavery in any territories acquired from the Mexican-American War, and the Fugitive Slave Act of 1850, which allowed for the recapture and return of escaped slaves to the South.
2. Free Soil: This position was held by many northern Democrats and some northerners in the Whig Party. Free Soil northerners believed that slavery should be restricted to the states where it already existed and should not be allowed to spread into new territories. They supported the Wilmot Proviso but opposed the Fugitive Slave Act of 1850.
3. Pro-Slavery: This position was held by a minority of northerners, particularly in the Democratic Party. Pro-slavery northerners believed that slavery was a necessary evil and should be protected by the federal government. They supported measures such as the Fugitive Slave Act of 1850 and the Kansas-Nebraska Act of 1854, which repealed the Missouri Compromise of 1820 and allowed for the spread of slavery into Kansas and Nebraska.
It is important to note that these positions were not always clear-cut and there were many northerners who held nuanced views on slavery. Additionally, the position of northern leaders and politicians on slavery could change over time in response to events such as the Fugitive Slave Act of 1850 and the Kansas-Nebraska Act of 1854.