Comma inside or outside quote in the middle part of a sentence?

Tolley is usually the master of all on this forum -- but here I disagree.

In the United States, the convention -- supported by several style guides, Chicago, MLA, and AP come to mind -- is that commas and periods are always placed inside the quotation marks. (See the post "Quotation Marks and other Punctuation - Inside or Outside" under FEATURED: WRITING TIPS & TRICKS.) In British English, the convention is reversed.

I recently learned that both American and British English placed the comma and period inside the quotation mark until about 120 years ago. Apparently, the small size of the moveable metal type for commas and periods needed a larger piece of type -- the quotation mark -- to hold it in place. When the Linotype machine was invented,  this mechanical brace became unnecessary. The Americans stayed with the original custom, while the British decided to adopt a more "logical" placement.

I hope this helps. 

I agree with Jeff. In the US the comma ALWAYS goes inside the quotation marks.