On July 7, 1898, President William McKinley signed the Newlands Resolution in the White House, formally annexing the Hawaiian Islands as a United States territory. The resolution passed Congress after weeks of debate, with the House voting 209 to 91 in favor and the Senate approving it days earlier. This act brought roughly 110,000 Hawaiian residents under American sovereignty and added 6,400 square miles of Pacific territory to the nation's domain. The islands would remain a territory for 61 years until achieving statehood in 1959.

The push for annexation had been building for decades. American missionaries and businessmen had long held influence in Hawaii, controlling much of the sugar and pineapple trade. In 1893, American-backed forces had overthrown the Hawaiian monarchy, installing a provisional government that immediately requested annexation. However, President Grover Cleveland opposed the takeover and ordered an investigation, delaying action for five years. When William McKinley took office in March 1897, he favored expansion and made annexation a priority.

The timing proved strategic. The Spanish-American War, which began in April 1898, highlighted Hawaii's value as a military outpost and coaling station for ships bound to the Philippines and other Pacific destinations. Supporters argued the islands were essential to American naval power and commerce in the Pacific. Some congressmen also invoked racial and civilizational arguments typical of the era's imperialist rhetoric. The resolution succeeded by portraying annexation as both economically necessary and a natural extension of American strength.

The annexation marked a turning point in American foreign policy and Hawaiian history. It ended the kingdom's independence and began the gradual erosion of Hawaiian culture and indigenous sovereignty. For the United States, Hawaii became the springboard for deeper involvement in Pacific affairs and Asian markets, cementing American presence in waters previously dominated by other powers. The islands' strategic military location would prove crucial during World War II when Pearl Harbor became the site of Japan's devastating 1941 attack.