Festivities are already under way in Duluth for Saturday’s 40th running of Grandma’s Marathon which is expected to draw 70 thousand people. Spokeswoman Kate Kucinski says tonight’s William A. Irvin 5K is a totally revamped course — a tour of historic Canal Park and downtown Duluth, and near the finish the participants will be running on the Lakewalk, right along Lake Superior, under the Aerial Lift Bridge and finish at the ore boat. Grandma’s Marathon and the Garry Bjorklund Half Marathon are tomorrow. Over 20-thousand runners are registered for the three races — the largest number ever. Kucinski says participants are from 39 countries and all 50 states plus the District of Columbia. They range in age from 12 to 87.