Why did some Northerners in Congress disapprove of the Kansas-Nebraska Act? It could allow slavery to exist in Northern territories. It could force all Northern states to accept slavery. It did not allow for the expansion of the transcontinental railroad. It did not allow the people to decide the slavery issue for themselves.

The correct answer is:

It could allow slavery to exist in Northern territories.

Explanation:

Stephen A Douglas, a senator of Illinois in order to organize the territories of Nebraska passed "The Kansas-Nebraska Act" in 1854.

His main aim was to set up a railroad that will cut through from Chicago to San Francisco, and passing through Kansas and Nebraska.

This Kansas-Nebraska Act of May 30th, 1854, created the territories of Kansas and Nebraska and opened new lands.

Some Northerners in Congress opposed and rejected the Kansas-Nebraska Act having the fear that it would allow slavery in Northern territories. However, Douglas explained this issue by stating that let the people settling in those territories determine if they would allow slavery within their boundaries.