09/09/1919
https://www.presidency.ucsb.edu...
"Therefore I, Woodrow Wilson, President of the United States, do hereby direct and prescribe that an Official Flag, indicative of the office of Secretary of State, be prepared as follows:"
"Whereas it frequently devolves upon the Secretary of State in virtue of the statutory authority conferred upon him to perform public acts of foreign intercourse under direction of the President;"
"And I further direct that on the approaching ceremonial visit of the Secretary of State to certain States of South America, the above prescribed flag shall be displayed on the national vessel which co..."
"And whereas it is proper that in the performance of such ceremonial acts as the representative of the President, it is appropriate his representative function be designated by an appropriate flag, to ..."