A primary source is a document written or created during the event.
Primary sources may also be created at a later date by those who have participated in the event.
Primary sources include: autobiographies, diaries, speeches, letters, minutes, interviews, journals, narratives, memoirs, images, news film footage, autobiographies, official records, oral histories, and photographs.
This guide is a collection of mostly primary sources on a variety of eras/events related to the topid of the U.S.as the world's policeman. Tabs will lead you to collections of information on that particular topic.
Image source: James Montgomery Flagg. 44-PA-71. National Archives and Records Administration. Public domain.