Final answer:
After the passage of the Fugitive Slave Act, Canada became the primary destination for runaway slaves seeking refuge from the strict enforcement and severe penalties imposed by the act.
Step-by-step explanation:
The destination for runaway slaves after the passage of the Fugitive Slave Act was primarily Canada. This act, part of the Compromise of 1850, made it increasingly dangerous for runaway slaves and free blacks in the United States. Since the federal law required all citizens to assist in the capture of fugitive slaves, and commissioners were incentivized to rule in favor of those claiming to be slave owners, many slaves and free blacks felt unsafe, even in northern states that had abolished slavery.
Northern abolitionists formed vigilance committees to protect runaway slaves, and some states passed 'personal liberty laws' to counteract the federal law, but these efforts could not guarantee safety to every black person at risk. Therefore, Canada became the primary refuge, due to its location beyond the reach of U.S. slave catchers and the relative safety it provided from the threat of recapture and enslavement.