A Mason City company which was one of the first in the world to make graindryers is closing its doors. Grain Systems International of Assumption, Illinois, has announced the closing of David Manufacturing Company in Mason City, due to the downturn in the agriculture economy. The closing means 97 employees are out of work onNovember 21st. Officials at David Manufacturing say they are veryappreciative of the offers of assistance by the mayor’s office and theoffice of economic development to ensure as smooth a transition as possiblefor the employees, and will be working closely with them in the next fewweeks.