n [ U ]
a phrase much used in 19th-century America to mean the right of the US to own and occupy land across the continent to the Pacific Ocean. It was first used in 1845 by John L O’Sullivan, editor of the United States Magazine and Democratic Review . He wrote that the US should ‘overspread the continent allotted by Providence for the free development of our yearly multiplying millions’. The idea of manifest destiny involved taking a lot of land belonging to Native Americans , especially in Oregon , and taking California and Texas from Mexico, which led to the Mexican War .