Explain two reasons for a president's expansion of power, and provide an example for each.

War and return power to the states: Lincoln and Jackson as examples.

During war, Lincoln suspended hapeaus corpus as a means to suppress Confederate support in the North. It was used as a means of safety and protection during wartime.

Jackson extended his power over the Supreme Court overriding their decision in Worcester V. Georgia and Cherokee Nation v. Georgia. He did this to return the power back to the state which is where he believed the issue belonged. He did this in dismantling of the National Bank as well. 

Contributing factors  leading  to the harlem renaissance were the great migration of african americans to northern cities, which concentratedambitious  people in places where they could encourage each  other, and the first world war, which had created new industrial work opportunities for tens of thousands of people.