-Manifest Destiny, a phrase coined in 1845, is the idea that the United States is destined—by God, its advocates believed—to expand its dominion and spread democracy and capitalism across the entire North American continent.
-There are three basic themes to manifest destiny: The special virtues of the American people and their institutions. The mission of the United States to redeem and remake the west in the image of the agrarian East. An irresistible destiny to accomplish this essential duty.
-Like the land to the west of the Mississippi back then, the national parks are giant unclaimed territory undisturbed by mankind, for now. Another aspect of manifest destiny that exists today I found is the idea of the United States wanting to spread their religion and culture to other parts of the world.
Hope this helped :)