ACT® · English: Punctuation Conventions
Semicolons in a Complex Series
When items in a list already contain commas, use semicolons between the items instead, so the reader can tell where one item ends and the next begins.
A normal list uses commas between items: apples, pears, and grapes. But if the items themselves already contain commas, stacking more commas between them buries the boundaries. 'We visited Austin, Texas, Reno, Nevada, and Mobile, Alabama' reads as a pile of six vague pieces, not three cities with states. The fix is to upgrade the dividers between items to semicolons: Austin, Texas; Reno, Nevada; and Mobile, Alabama. Now every semicolon marks a clean break between items, and every comma stays inside an item doing its normal job of attaching the state to the city.
This looks like the semicolon's famous job of joining two complete sentences, but it isn't. Inside 'Dr. Nwosu, a cardiologist; Ms. Petrov, an attorney; and three residents,' nothing on either side of the semicolons is a full sentence. The semicolon here is just acting as a stronger comma, promoted because the regular comma is already taken. Context tells you which job it's doing: two independent clauses means the joining job, a list with internal commas means the divider job.
The rule is triggered by even one messy item. If a bid names 'a mill in Duluth, a foundry in Gary, Indiana, and a shop five miles away,' only the Gary item has an internal comma, but that's enough: every divider in the whole series upgrades to a semicolon, giving 'a mill in Duluth; a foundry in Gary, Indiana; and a shop five miles away.' This connects to how semicolons normally join clauses and to how colons introduce lists; the series semicolon is a special, list-only use of the same mark.
Key terms
- Complex series
- A list whose individual items already contain internal commas.
- Series semicolon
- A semicolon used to separate items in a complex series instead of joining two clauses.
- Independent clause
- A group of words with a subject and verb that could stand alone as a sentence.
- Divider
- The punctuation mark placed between items in a list to show where one item ends and the next starts.
Watch it explained
- How it worksHow does upgrading the dividers to semicolons keep a list of comma-carrying items readable?
- Common mistakeWhy isn't the semicolon here doing its usual job of welding two complete sentences together?
- Going furtherWhat changes when only one item in a long list carries an internal comma of its own?
Check yourself
End of topic.