2 Working with Historical Sources

Sources as historical evidence

Historians evaluate sources and use them as evidence about the past. A source does not speak for itself: its meaning depends on the question being asked, who created it, and the circumstances in which it was made.

Classify sources by the question

A Primary source was created during the period or events under investigation, or by someone with direct experience of them. Examples include letters, laws, photographs, speeches, oral histories, maps, objects, and government records. A Secondary source is a later account or analysis that interprets evidence, such as a history textbook or scholarly article.

These categories depend on the research question, not only on the type or date of an item. A memoir written years after an event may be primary evidence for studying the author's later recollections, and it may also help investigate how the event was remembered more broadly. A textbook explaining an earlier event is secondary, but it can be primary evidence for studying how people taught history when the textbook was published.

Observe before interpreting

Begin by observing what the source actually contains. Note its type, date, creator, details, and any unfamiliar language or features. Keep direct observations separate from interpretations: “The letter asks for more workers” describes content, while “the writer was worried about a labor shortage” is an inference that needs to be tested.

A useful first stage is to observe, reflect, and ask questions. Analyze a document before using it as evidence; this approach is also reflected in guidance from the Library of Congress and the National Archives.

Investigate origin and context

Examine the source's origin and circumstances by asking about its authorship, audience, purpose, and historical context.

• Authorship: Who created the source? What role, knowledge, beliefs, or interests might have shaped that person's perspective? If the creator is unknown, consider what can and cannot be inferred from the source itself.

• Audience: Who was expected to read, hear, or view it? A private letter to a trusted friend may differ from a public speech aimed at voters.

• Purpose: Why was it made? It might inform, persuade, record, justify, entertain, or commemorate. Consider what the creator wanted the audience to think or do.

• Historical context: What political, social, economic, and cultural conditions were present at the time? Context can help explain a source's language, choices, and silences. Avoid assuming that people in the past shared modern values or meanings.

Evaluate limits and perspective

Ask what a source can and cannot show. Consider whether it is complete, accurate, representative, and close in time to the events it describes. It may omit facts, reflect a limited viewpoint, use unfamiliar terms, or have been edited, translated, or preserved unevenly.

Bias does not automatically make a source useless or false. For example, a persuasive speech may be strong evidence of what its speaker wanted an audience to believe, even when it is not a neutral account of events. Evaluate a source in relation to the question and the claim it is being used to support.

Compare and corroborate sources

Corroboration means comparing sources to see where they agree, differ, or leave gaps. Agreement among independent accounts can strengthen a conclusion, but multiple sources may repeat one original report or share the same limitations. Disagreement can also be valuable because it may reveal different interests, experiences, or interpretations.

For an investigation of a workers' strike, a researcher might compare a worker's letter, a newspaper report, an employer's records, and a later historian's account. The letter may reveal one worker's experience; the newspaper may show how the event was presented to readers; company records may document business decisions; and the later account may connect the strike to wider developments. None of these sources alone necessarily describes the whole event.

Build a qualified argument

An evidence-based historical argument answers a focused question with a claim supported by relevant evidence. Explain how each piece of evidence supports the claim, and acknowledge important limits or conflicting evidence.

Avoid saying that a source simply “proves” an explanation. For instance, rather than claiming that a source proves low wages caused a strike, identify what the source says, who produced it, and why it supports—or only partly supports—that explanation.

A useful sequence is:

1. Identify the question and the source's type, creator, and date.

2. Describe relevant content accurately.

3. Analyze authorship, audience, purpose, and context.

4. Evaluate what the source can establish and what remains uncertain.

5. Compare it with other evidence and use it to support a qualified conclusion.