Growth of the railroads.The government gave the railroad companies huge amounts of land for every mile of track laid. This land was used to develop new towns and cities, greatly reducing the area of free pasturage available to cattle owners for their herd.
Increasing numbers of new immigrants. Many of these European immigrants set up as sheep farmers, which required much less capital investment than cattle farming. The sheep farmers fenced off their land, further reducing available free pasturage for cattle, and additionally denying access to vital water sources for the cattle herds.
It all depends on your personal beliefs now and days. some people believe it started from a bang, others believe that God from the bible created everything, and others believe that there are multiple gods that created the universe and everything. I say you do some research and figure out which of the hundreds of tales you believe.
hope this helps
