In the early days, hay was often cut with hand scythes, pitchforked
onto a wagon and then stacked in a barn. This was common in wetter parts
of the country, but in the arid West, ranchers learned that the hay did
not need to be covered. Ten inches of annual precipitation, including
melted snowfall, wasn't enough to cause hay to mold.
Once they no longer needed to haul hay off to distant barns, ranchers
started looking for the best way to build haystacks right in the fields
where the hay was cut. In 1908, the "beaverslide hay stacker" was
invented in the Big Hole Valley in Southwestern Montana. It remains in
use on many Montana ranches today.