Closest city to Mount Rushmore is Rapid City, which is about 3 hours flying time from Chicago. Aer Lingus flies to Chicago where you can connect with an onward flight. If you were to drive from Chicago, Mount Rushmore is about 780 miles. Best way to see South Dakota is to take a car. South Dakota tourism have a very good web-site where you can also see a panoramic image in real time of Mount Rushmore - the address is: www.travelsd.com.