Collections have been divided into categories, but researchers should be aware that some collections could easily fit into more than one category. Alexander Haig was one of many officials and policymakers who began his career in the armed forces. After becoming a general officer in the US Army, he built a government career that led to positions as White House chief of staff and US secretary of state. A description of his papers is located in the “Policy” category, but could also fit into the “Military” or “Diplomacy” categories. Likewise, the papers of diplomat Philip C. Jessup are not found in the Diplomacy category but are instead described under “Citizenship and Loyalty” because of the substantial number of files concerning his investigation by Senator Joseph McCarthy.

In addition, many collections contain material dated outside the commonly accepted period of the Cold War from 1947 to 1991. The material appears in this list because it helps detail events and circumstances that led to the Cold War, or explains the aftermath.