What countries were involved in manifest destiny?

Manifest Destiny primarily involved the United States, as it was a doctrine that justified the expansion of U.S. territory across North America in the 19th century. This concept often led to conflicts with Mexico, particularly during the Mexican-American War, resulting in the U.S. acquiring significant territories, including present-day California, Arizona, New Mexico, and others. Additionally, it impacted relationships with Indigenous peoples and other nations, such as Great Britain, regarding territorial claims in the Pacific Northwest.