What invention was a major contributor to the end of the open range on the great plains

One factor was barbed wire. As farmers and ranchers wisened up, they used the wire to fence in their cattle, destroying the use of cowboys, and taking away one aspect of the "wide open west".  Herds of cattle took over the plains and destroyed the grass. In 1883 the big drought struck and water streams dried up and prairie fires grazed. Also the barbed wire and the natural disasters.

the answer is: must pay taxes on profits

since it is considered as a part of your income, profits from investments is eligible for tax payment.

the tax from your investment could be influenced by how long you decided to sell it. united states promotes keeping your investment for long term period. so, the tax rate for investments that you sell in less than one year is typically higher compared to investments that you sell in more than one year period.