Why did the government leaders believe that expansion westward was in the nations interest?

Government leaders believed that westward expansion was in the nation's interest for several reasons, primarily economic growth, national security, and the belief in Manifest Destiny. Expanding territory was seen as a way to promote agriculture, access Natural Resources, and stimulate trade. Additionally, leaders felt that spreading American democratic ideals and culture would strengthen the nation and secure its borders against foreign threats. This ideology fostered a sense of national pride and unity, driving the push for expansion.