SIOUX FALLS, S.D. (KELO) -- Downtown Sioux Falls is celebrating America's 250th with another Open Streets event on Friday. Becky McElroy is preparing for another day at Mary's Mountain Cookies in downtown Sioux Falls. "So, as you can see, we bake a lot of different flavors of cookies. We have 21 fla vors of cookies in [...] ...read more read less