How to Make a Chronology

A chronology is a record of events in the order they happened. Historians build them to establish what came before what, lawyers build them to lay out the facts of a case, and writers build them to keep a long story straight. Most of the work is not the drawing. It is deciding which events belong, finding a date for each one, and being honest about the dates you cannot pin down.

Chronology or timeline?

In everyday use the two words point at the same thing, and you can treat them as interchangeable. Where they pull apart is emphasis. "Chronology" emphasizes the ordered record itself, so it often describes a list: dated entries, one after another, each with the detail behind it. "Timeline" emphasizes the picture, where the same events sit on a date axis and you read spacing and overlap off the drawing.

That is a presentation choice rather than two different pieces of work. The gathering below is the same either way, and the same set of events can be shown as a list or as a graphic. If you want the distinction between a chronology and a plan people work from, see Timeline vs Schedule.

1. Decide what it covers

Write down the span and the subject before you collect anything. "The Apollo program, 1961 to 1972" and "everything that led to the moon landing" are very different jobs, and the second one has no natural stopping point.

Decide the level of detail at the same time. A chronology of a war that records every skirmish is a different document from one that records the treaties, and mixing the two makes both harder to read. Pick the grain you want and hold to it.

2. Collect the events

Work source by source rather than date by date. Read a source through, pull out every event in it that fits your scope, and note where each one came from. Jumping between sources to fill gaps in date order means reading each one several times and losing track of what came from where.

For each event, capture the name, the date, and enough of a note that you will still understand the entry in six months. Record the source in that note. A chronology whose entries cannot be traced back is hard to correct and hard to defend, and if the chronology is for a court, a paper or a client, the sources are half of what it is for. See Cite a Timeline if you need to be cited in turn.

3. Settle the dates

Dates are where chronologies go wrong. Three problems come up over and over.

Sources disagree. Pick the one you trust most, use it, and say in the note that the others differ and what they say. Do not average them.

The date is partial. Plenty of events are known to a month or a year and no closer. Record the precision you actually have rather than inventing a day, and if you need the precision recorded explicitly, put it in the note.

The calendar changed. Dates before the Gregorian changeover, and non-Gregorian calendars generally, need a note saying which calendar the date is in. Converted dates should say they were converted.

Once the dates are settled, put them into a consistent format so the whole document reads the same way.

4. Group what belongs together

A long flat list is hard to read past about thirty entries. Grouping is what makes a chronology usable: by strand of the story, by party involved, by place, or by phase.

Grouping also makes gaps visible. A strand with nothing in it for four years is either a quiet period or a hole in your research, and a flat list hides which.

5. Read it back

Read the finished chronology start to finish as a document rather than as a list of entries. You are checking three things: that every entry is in the right place, that anything you would have to explain out loud is explained in the note, and that nothing sits there undated because you meant to come back to it.

Building one in Preceden

Preceden gives you the dated record and the visual in the same document, so you do not have to keep a list and a graphic in step by hand.

Create a timeline, then add an event for each entry. The name and the start date are the only required fields. Give an event an end date as well when it covers a period rather than a moment, and Preceden draws it as a bar instead of a point.

Put the source and any explanation in the event's Notes field. Notes show when you hover an event and in the list of events below the timeline, and they accept markdown formatting and links, so a citation can point at the source it came from.

For partial dates, type what you know. Preceden accepts a bare year, a month and year, a full date, and times of day, and it also handles BC and AD dates from 240,000 BC onward, which matters for anything ancient. Supported Date Formats lists what it reads. If your events have no dates at all and only an order, Dateless Timelines covers the stand-in dates workaround.

Use layers for the grouping in step 4. One layer per strand, party or phase gives each its own section of the timeline, and the gaps show up as empty stretches.

If your events are already in a spreadsheet, import the CSV or Excel file rather than retyping them. To hand the finished chronology to someone else, export it as a PDF, share a link, or embed it in a page of your own.

Keeping it current

A chronology for a live matter is never finished, so leave it in a form you can add to. Events can be added, edited and moved between layers at any time, and the Bulk Editor gives you a spreadsheet-style view when you want to work through many entries at once rather than opening them one by one.