Northerners opposed the expansion of slave states in the U.S. territories during the 1800s due to concerns about political dominance, economic implications, and the balance between free and slaveholding states.
Northerners in the debate over U.S. expansion in the 1800s, particularly opposed the idea of new territories joining as slave states. They were concerned about the political dominance of the South and the economic implications of spreading slavery westward. They feared that allowing slavery to expand would lead to a skewed balance between free and slaveholding states, affecting the nation's future.
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