Why did people migrate to the western frontier lands?

Explanation:

Migration has been an important force in the development of America. Ever since the English settled along the banks of the James River in 1607, subsequent generations have looked beyond the boundaries of their settlements to the unsettled regions of the west. These people realized that the advancement of their civilization was dependent upon a continuous supply of mobile humans who were willing to pack their belongings and their families, to relocate to another part of the continent, to transplant their culture, and to resume life in a new environment. Since the American nation was founded and developed on the basis of this westward orientation and on a belief that God had predestined the American people to fill the nation to its natural boundaries, one can easily conclude that migration has been, and continues to be to this day, a distinct characteristic of America and its people, so much so as to earn the population the title of a "People in motion."

the answer is b.2008 and 2012 were presidential election years.