How do we know what happened at Jamestown in 1607 or in Philadelphia in 1776? Nobody alive today was there. Historians work like careful detectives: they gather evidence left behind by the past and reason from it. The first question to ask about any piece of evidence is simple: who made it, and when?
Key idea
A primary source was made at the time, by someone who saw or took part in the events: a letter, a diary, a law, a map, a speech, a photograph, a tool dug from the ground. A secondary source was made later by someone studying the events from other sources: a textbook, a history book, a documentary.
Why it works
The line between the two is about distance from the event, not age. A primary source lets you hear a voice from the time, with its details, its feelings and its blind spots. A secondary source steps back: its author has read many primary sources, compared them and offers an explanation. Historians need both. Primary sources are the raw evidence; secondary sources are arguments built from that evidence, and they can be checked against it.
Worked example: Primary or secondary?
A history of the founding of Virginia, published in 1910 and based on the colony's old records.
- Ask when it was made: 1910.
- Ask when the events happened: Jamestown was founded in 1607, about 300 years earlier.
- Ask who made it: an author who studied records, not someone who was there.
Answer: A secondary source. It is old, but it was made long after the events by someone studying them.
Worked example: Primary or secondary?
The Mayflower Compact, the agreement the Pilgrim men signed on board their ship in November 1620.
- When was it made? In 1620, at the very moment it describes.
- Who made it? The people who were forming the government.
Answer: A primary source: it was made by participants, at the time.
Common mistake
Two mix-ups are common. First, calling anything old a primary source: a 1910 history of the Revolution is old, but secondary. Second, treating a primary source as true because it was there. When Christopher Columbus wrote in 1493 that the island people he met had "no kind of government," he could not speak their language and had stayed only a short time. His letter is excellent evidence of what Columbus believed and wanted his readers to think; it is weak evidence about Taíno government. Check every source, primary or secondary, against others.
Some sources can be both, depending on your question. Mercy Otis Warren lived through the Revolution and published a history of it in 1805. For the events of the war, her book is a secondary history; for how a Patriot writer of the time saw the war, it is a primary source.