What caused many northerners to be more aware of human cost of slavery?

Many northerners became more aware of the human cost of slavery through various factors, including the publication of powerful abolitionist literature, such as Harriet Beecher Stowe's "Uncle Tom's Cabin," which vividly depicted the brutal realities of enslaved life. Additionally, firsthand accounts from formerly enslaved individuals and the growing abolitionist movement highlighted the moral implications of slavery. The increasing visibility of the Underground Railroad and the participation of free blacks in advocating for emancipation also contributed to shifting perceptions in the North. These combined efforts fostered a greater awareness and moral outrage regarding the injustices of slavery.