Comma After a Long Introductory Prepositional Phrase
The Comma
Rulebase Summary
Use a comma after a long introductory prepositional phrase (four or more words). Short, specific prepositional phrases at the beginning of a sentence generally do not need a comma. However, some short general or transitional prepositional phrases (e.g., 'in fact,' 'by contrast,' 'as a rule,' 'of course,' 'in any case') are set off because they contrast, restate, illustrate, or affirm.
Examples
A. At the intersection of Oak Street and Vine Avenue I noticed the traffic light was out.
A. At the intersection of Oak Street and Vine Avenue, I noticed the traffic light was out.
Comma after a long introductory prepositional phrase.
A. In the early morning hours of September 15th we received the call.
A. In the early morning hours of September 15th, we received the call.
Four-plus words — comma after the introductory phrase.
Transcript Notes
Short prepositional phrases acting as simple modifiers do not need a comma. Long ones (generally four or five words or more) do. However, always use a comma after an introductory prepositional phrase — regardless of length — when: (1) there are two or more prepositional phrases in a row, (2) the phrase has an internal comma, (3) the phrase contains a dependent clause, or (4) the phrase contains a verbal. These rules apply to simple modifiers, not parenthetical phrases.
Prepositional phrases that are out of their natural word order in the middle of the sentence and interrupt the flow also need a pair of commas. A single short prepositional phrase mid-sentence may not need commas — it depends on how interruptive it is. When in doubt, keep the punctuation simple and leave it out.
Style Guide References (8)
Morson's
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