What was a major reason for u. s. empire building?

To spread their democracy and power throughout the world, more land also means the potential to make more money and have more influence.

slavery, abortion, donald trump, gay marriage, racial rights, immigration  

explanation:

anything that has been broth up to the supreme court is something of grate political divide   so just look as court cases

a countries leader should be motivated by the common good of the country.