Style

US English: Place ending punctuation inside the quotation marks

The following text is taken verbatim from the book, 300 Days of Better Writing: A daily handbook for improving your writing written by David Bowman (2010)

“(Note to our friends in Great Britain: reverse the tip in the next paragraph, and you will probably do fine.)
When providing a direct quote or using quotation marks to indicate that you are writing about a word or phrase, the comma or period that ends the phrase or sentence should be placed inside the final quotation mark. (GB: outside the final quotation mark)

Examples:

John said, “I am in love with Julie.”
Many people don’t pronounce the final sound of the words “fast,” “quit,” and “stop.” When the man shouted “Halt,” I ran away.

However, if your final punctuation is a question mark, semicolon, or colon, and if that punctuation mark is not part of the quote, then it should go outside.

Example:

Did the boss say “fire everyone you can”?
(Note: We removed the quotation marks from around the examples so the quotation marks we’re trying to indicate are obvious.)”