The main reason why Spain decided to support Columbus' voyages of exploration was because he promised that he would bring gold and spices back from the New World. Another reason was that the Spanish Crown was interested in spreading Christianity.
The answer is the US of A
I believe the answer is Barbed Wire.
Befor the inventions of barbed wire, the Cattles are let to roam freely across the plains and the owners are required to pay a lot of cowboys to supervise them so they didn't go missing. Witht he invention of barbed wire, they can keep the cattle in a secure place without supervision.
