This is a great question. While United States Americans are taught about 'manifest destiny' in school (a very whitewashed, biased version), and it was a concept that greatly shaped the United States - both ideologically and by international borders - it is truthfully only the continuation of a European tradition - the same tradition that inspired the very founding of the first European colonies in North America and their associated conflicts, such as the Anglo-Powhatan Wars and Pontiac's War, and continues on in insidious ways today, especially apparent now in the Levant, Afghanistan, and even the South China Sea. In schools in the United States, we are taught that 'manifest destiny' was the moniker of a long-ago zeitgeist, something that doesn't really affect us anymore, but that is very far from the truth. It is only a poetic pseudonym for the spirit of a resurgent United States American imperialism. The ideology as it was when it was defined was wholly, unapologetically racist and fostered by racist white United States American columnists and pedagogues. The racism and the peddling of imperialism practised these days by the commentariat is only less outright, relying on dog-whistles and suggestion. It was a period of great, bombastic violence, such as the Trail of Tears and the war against Mexico, that cost many non-white communities their lives, land, and cultures. Now United States imperialism is more strategic or much farther from the continent, and thus much easier to ignore. But, as I'll repeat one last time, it has never left the U.S.. While it may have been imported from Europe alongside a culture of war and conquest, what would eventually be known as 'manifest destiny' became a monster in its own right, and would most notably be exported back into Europe and interpreted as Lebensraum by the German NSDAP. It looks like I've run out of space to write but if you have any questions about what I wrote, feel free to ask and I will be happy to answer!