Scattered on the eastern plains are windmills or windpumps. A problem facing farms and ranches on the plains was providing a satisfactory supply of water for their cattle. These windpumps are used on farms and ranches in the central plains and South West of the United States. The farm wind pump was invented by Daniel Halladay in 1854. Eventually steel blades and steel towers replaced wooden construction, and at their peak in 1930, an estimated 600,000 units were in use. The multi-bladed wind turbine atop a lattice tower made of wood or steel hence became, for many years, a fixture of the landscape throughout rural America. This year marks the 156th anniversary of the first commercially operated windmills.