Take a look at the two basic ways that commas are used: All commas are used to either separate two language elements and push them apart or to surround a language element. The latter implies that the element, if lifted out of the sentence, would take both commas with it and leave a grammatically complete sentence behind.
…As the session began, it seemed there was no agreement.
…Do you intend to prolong this, Counsel?
…It is futile to continue this discussion, in my opinion.
…It seemed, as the session began, there was no agreement.
…Do you, Counsel, intend to prolong this?
…It is futile, in my opinion, to continue this discussion.
The question has recycled lately on FB regarding whether or not to use a comma after the full date when it is a direct adjective. This discussion also applies to the city/state combination as a direct adjective. The rules above do not change because the full date or the city/state are direct adjectives.
…I am referring to the January 8, 2015, letter that he sent.
…I am referring to the January 8 letter that he sent.
…I am referring to the January 2015 letter that he sent.
…It is the Rochester, New York, location.
…It is the Rochester location.
The confusion here comes from a rule that says to not use a comma between the adjective and the noun it modifies. That rule refers to a single separating comma. A pair of commas can go anywhere.