Hay served for almost seven years as Secretary of State , under President McKinley , and after McKinley 's assassination , under Theodore Roosevelt . Hay was responsible for negotiating the Open Door Policy , which kept China open to trade with all countries on an equal basis , with international powers . By negotiating the Hay – Pauncefote Treaty with the United Kingdom , the ( ultimately unratified ) Hay – Herrán Treaty with Colombia , and finally the Hay – Bunau-Varilla Treaty with the newly-independent Republic of Panama , Hay also cleared the way for the building of the Panama Canal
McKinley 's assassination
Assassination of William McKinley
John Hay