I am thinking the Statue of Liberty
Before the USS Maine exploded, the United States was trying to expand as a world power. Thus, many Americans blamed Spain for the explosion of the USS Maine because it gave them a reason to declare war on Spain and take control of Spanish territory in the Pacific and Caribbean.
Many settlers were willing to leave their homes and head west due to the dream of attaining a better life, usually thinking of the possibility of acquiring free or cheap land. Other ocassions were for example, the "gold rush" in which so many went to California in search of gold. Others went west hoping to find more freedom.