When the Supreme Court declared Section 3 of the federal Defense of Marriage Act unconstitutional, 13 jurisdictions in the US permitted and recognized same-sex marriages. That meant for those same-sex couples who entered into valid marriages in those jurisdictions, their marriages would be recognized by that state and by all federal agencies.
Pennsylvania has its own DOMA law and does not recognize same-sex marriages. However, for a brief time Montgomery County, a suburb of Philadelphia, was issuing same-sex licenses. On September 12, 2013, a Pennsylvania judge stopped a Montgomery County official from issuing marriage licenses to same sex couples stating that it was a clear violation of his legal authority. Currently, it is unclear what the effect the law will have on the 174 couples who already obtained licenses, ie whether the state of Pennsylvania will recognize their license.