Pre-1861 U.S. foreign relations materialsOnline research guide from the Office of the Historian The Office of the Historian is staffed by professional historians who are experts in the history of U.S. foreign policy and the Department of State and possess unparalleled research experience in classified and unclassified government records. The Office’s historians work closely with other federal government history offices, the academic historical community, and specialists across the globe. The Office is directed by The Historian of the U.S. Department of State.