How did william mckinley change the world?

During McKinley's presidency, the United States proved its prowess as the war with Spain, a strong European power, was fought and won. As a result, America gained overseas territories and influence in Asia, and then the President tried to normalize trade with China when he issued his "Open Door Policy." Hawaii, which eventually became the 50th U.S. state, was annexed in 1900. During this period the United States established itself as a world power. Some historians believe that one thing President McKinley did for the nation was inadvertent when he made the decision to pick Theodore Roosevelt as his running mate for the 1900 election, and as a consequence, bequeathed the presidency and the welfare of the country to him