What did the settlement of the West mean to the white cattlemen?

At first, the settlement of the West helped cattlemen, but
eventually, it forced them to drastically change their way of
life.

Originally, it was the settlement of the West that
allowed cattlemen to have a place to settle and to keep their herds.  It was the
extension of railroads that allowed them to get their beef to markets and it was the
Army that drove Indians off the land that they used for their
herds.

Eventually, however, the settlement of the West
forced changes.  As farmers came to dominate much of the West, cattlemen could no longer
simply allow their herds to roam.  As land became more settled, the cattlemen had to
keep their cattle much more penned in.  This need (along with the invention of barbed
wire) led to the end of the era of the open range and the cowboys who were needed to
herd open-range cattle.