How often are aurorae seen in the continental United States?

Despite the fact that most of the states are located well below the zone of most activity near latitudes of 68 degrees, we get quite a number of Aurora Borealis sightings, even as far south as Arizona! Here is a partial list that I culled from back issues of Sky and Telescope magazine:

Date....................Sighted from..............Sky and Telescope Issue
August 1, 1959          Rochester, New York           November 1959
August 19-20, 1963      Fargo, North Dakota           October, 1963
July 8, 1966            Lake Placid, New York         December, 1966
September 3, 1966       Saint Paul, Minnesota         December, 1966
September 29, 1969      Pompton Planes, New Jersey    December, 1969
October 17, 1970        Birmingham, Ohio              December, 1970
June 17-18, 1972        Over the Great Lakes          August, 1972
July 5-6, 1974          Toronto, Canada               October, 1974
May 2-3, 1976           Bucyrus, Kansas               September, 1976
August 28, 1978         Walla Walla, Washington       December, 1978
April 10, 1981          Tucson, Arizona               July, 1981
After 1981, Sky and Telescope stopped reporting aurorae! You can see that about every 2-3 years we get a good show 'down here'!!