MITCHELL — Visitors approaching the Corn Palace Plaza were greeted with a familiar, patriotic sight — the traditional red, white and blue American flag hoisted above the ground from a Mitchell Fire Department ladder truck. As it fluttered in the breeze Tuesday evening, Mark Nelsen, owner of Maximum Promotions in Sioux Falls, darted about making preparations for what was to come next. In a few minutes, the huge flag was taken down and folded prop…