What factor led to increased tensions concerning slavery in the United States?

Answer: Prior to the Civil War the economies of the North and the South developed differently in the early 1800s. Although both economies were mostly agricultural, the North began to develop more industry and commerce. By contrast, the Southern economy relied on plantation farming.

Explanation:

The issue of slavery caused tension between the North and the South. In the North, the antislavery movement had slowly been gaining strength since the 1830s. Abolitionists believed that slavery was unjust and should be abolished immediately. Many Northerners who opposed slavery took a less extreme position.