Calks are knob-like structures that are placed on a horseshoe to keep the horse from slipping. Calks are placed on the ends of the shoe and/or on the toe. Parallel calked horseshoes have their calking placed in the same direction or are parallel to each other. While the perpendicular calked horseshoes have one of the calks facing forward and the other facing sideways or are perpendicular to each other. Parallel calked horseshoes were commonly used by blacksmiths. However, the perpendicular calked horseshoe may be the unique invention of their one-time owners, the Chesebro blacksmiths of Saunemin Illinois. Horseshoes were changed according to ground conditions and if a horse was not shoed appropriately, it could have been not only dangerous to the horse, but harmful to the people and goods the horse was carrying or pulling. In comparison to the parallel calks, we suspect that the perpendicular calks created better traction and stability for their customers' horses. How we learn about communities; American communities in history. 16 History; 13 Science, Technology and Society; 18 Social Systems; 15 Economics.