Mr. Dempster was aware of these homesteaders would need water pumps, machinery and tools to survive and prosper. A manufacturing plant was built to produce windmills, hand pumps, water well products and agricultural implements. During the years following, Dempsters produced hundreds of various products and machines for the water and agricultural industries. These included windmills, hand pumps, well cylinders, towers, well drilling machines, fly wheel type gasoline engines, water storage tanks, piston pumps, centrifugal pumps, jet pumps, submersible water well pumps, and vertical turbine pumps.

During the World War II era, Dempsters participated heavily in war production by producing more than 1 1/2 million 90-millimeter shells. In 1960, Investor Warren Buffett acquired the company from the Dempster family. During 1963, Dempsters Mill Manufacturing Co. was sold to a group of investors and the name changed to Dempsters Industries Incorporated. In 1985, the company was sold to Don Clark and was privately owned.