The significance of the Open Door Policy in U.S.-China relations was its aim to ensure equal trading rights for all nations in China while promoting U.S. interests in the region. Instituted in the late 19th century, it sought to prevent European powers from monopolizing trade and influence. The policy symbolized America's growing involvement in international affairs and commitment to preventing colonial encroachment in China. Although it faced criticism, the Open Door Policy laid the groundwork for U.S.-China relations and highlighted American aspirations for greater presence in Asia.