What motivations and justifications explain us expansion between the civil war and world war 1?

1.3.6 practice: examining the founding principles the declaration of independence we hold these truths to be self- evident, that all men are created equal. that they are endowed by their creator with certain unalienable rights, that among these are life, liberty, and the pursuit of happiness.- that to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed,- that whenever any form of governments becomes destructive of thee ends, it is right of the people to alter or to abolish it, and to institute new government, laying its foundation on such principles and organizing its power in such form, as to them shall seem most likely to effect their safety and happiness . summary