A primary source provides evidence from the time, event or activity being investigated; a secondary source interprets or analyzes evidence. The role depends on your research question. “Primary” does not automatically mean accurate, unbiased or more useful for every purpose.
An original town-library example
Imagine you are studying why a fictional town opened a library in 1925. None of the documents below is a real archival item; the scenario illustrates source roles.
| Hypothetical document | For the library's 1925 opening | A limitation |
|---|---|---|
| Town council minutes approving funding | Primary evidence of the recorded decision. | May not capture informal negotiation or every resident's view. |
| A 1925 newspaper editorial | Primary evidence of that editorial's contemporary argument. | Not a neutral account of all public opinion. |
| A later historian's book chapter | Secondary analysis of the opening. | Check its evidence, argument and publication context. |
| A current visitor photograph | Evidence of what was visible when photographed. | Does not prove what the building looked like in 1925. |
Now change the question: how did historians in 1980 describe public libraries? That 1980 book can become primary evidence of historical writing in its own period. Its classification changed because the question changed, not because the physical book changed.
Observe, reflect and question
The U.S. National Archives provides resources for finding and analyzing primary sources. A useful application is to separate what you directly observe from an inference and then identify the next question. For a letter, note its date, sender, recipient, medium and provenance before treating its statements as a complete account of events.
Ask who created the material, for whom, for what purpose and under what constraints. Consider what survives in the archive and what may be missing. One surviving record may be important without being representative of everyone involved.
Corroborate specific claims
If council minutes say a building opened on a date, compare an independent contemporary record where possible. If an editorial claims “everyone opposed it,” distinguish the writer's rhetoric from evidence of a measured population. Agreement between two documents is stronger when they did not simply copy one another.
A later synthesis can provide context, terminology and leads to evidence you would otherwise miss. Good research does not discard secondary scholarship simply because a primary document exists. It compares their roles and the strength of the particular claim.
Digital copies need provenance too
Check the catalog record, collection, date, transcription notes and any missing pages. A scan's upload date is not necessarily the document's creation date. A transcription can improve access but may omit layout or uncertain readings. Keep the stable record URL and the item/collection identifier where available.
Write an evidence-aware sentence
Instead of “The town wanted a library,” a more precise description of the hypothetical evidence is: “The council minutes record approval of library funding; the surviving editorial opposed the proposal, but these two documents do not establish the views of all residents.” That wording preserves what the sources show and what they cannot.
For checking an AI-generated citation to such a document, use the citation-verification workflow. For a digital timestamp problem, see publication dates versus update and archive dates.