Explain why Northerners favored the Wilmot Proviso and why Southerners did not.

The Northerners favored the Wilmot Proviso and the Southerners did not because they did not believe in slavery. The Wilmot Proviso stated that slavery will not exist in newly acquired territories from the Mexican war. For example, territories of Utah, New Mexico, and California would be closed to slavery forever.

powers  are  denied  to the  national governmentin three distinct ways: some  powers, such as the  power  to levy duties on exports or prohibit the freedom of religion, speech, press, or assembly, are expressly  denied  to the  national government  in the  constitution.