How was manifest destiny achieved during expansion of the United States during the early to mid 1800s?

Manifest Destiny was basically the term used to describe the obligation of the American people to expand the country from "sea to shining sea," or, in other words, form the east to west coast. During the 1800's, purchases and expansion occurred that overall just expanded the territory the United States claimed as its own and eventually the land acquired is what we know have as the United States.