Comma After an Introductory Adverb Clause
The Comma
Rulebase Summary
Use a comma after an introductory adverb clause regardless of its length. The comma is placed where the dependent clause ends and the independent clause begins. Adverbs that commonly begin introductory clauses include after, although, as, because, if, since, when, and where. Expressions like 'Just so I'm clear' may be treated as introductory clauses (comma) or as shortened prefaces (colon), depending on inflection and delivery.
Examples
A. When I arrived at the hospital the victim was already in surgery.
A. When I arrived at the hospital, the victim was already in surgery.
Comma where the introductory adverb clause ends.
A. Because the alarm had been disabled no one was alerted to the break-in.
A. Because the alarm had been disabled, no one was alerted to the break-in.
Comma after introductory 'because' clause.
Transcript Notes
Always use this comma regardless of how long or short the adverb clause is when it begins the sentence.
Style Guide References (2)
Morson's
BGGP