Because the us did not want to be together if some states did not agree with the others so they craeted two sides that divide the us
Answer:
Francisco Pizarro
After years of preliminary exploration and military skirmishes, 168 Spanish soldiers under conquistador Francisco Pizarro, his brothers, and their native allies captured the Sapa Inca Atahualpa in the 1532 Battle of Cajamarca.
It was Called the frontier because some or most of the areas in America that where settled by ranchers hadn't been explored or discovered yet.
