How did even northern states limit the freedoms of blacks even as they decried the expansion of slavery?

Answer: Passing laws that limited the movement and freedom of blacks

Explanation:

Even though the whites in the Northern territories viewed slavery as a moral wrong and a stain on the moral fibre of the United States, they did not believe that Black people should be entitled to the same rights as them.

To keep blacks at a certain social level and to limit the amount of blacks in their territories, some states passed laws that restricted the movements of blacks.

States like California and Kansas did it subtly while states like Iowa, Illinois and Indiana banned blacks entirely from their states.