Avoca sits right where the flat cropland starts folding up into the Loess Hills, and the wooded draws on that edge of town hold onto snow in the shade of bur oak and cedar long after the open fields have gone bare and muddy again. Knotty Wood Tree Service knows those properties from the tree work, which makes the winter driveways easier — knowing which limbs hang low enough to catch a truck, which yards drift deep against a windbreak of cedars planted long ago. A driveway scraped clean under that kind of tree cover, with the hillside snow still holding in the shadows around it, takes a careful hand with the blade. Pottawattamie County's western edge gets its own particular wind funneling up out of the Missouri River valley, and a hillside driveway in Avoca can ice over faster than a flat one in town ever would. Getting a customer's drive clear and salted before that ice sets into the grade is the whole job, done early on a short winter morning.