No they don't. The Defense of Marriage Act (DOMA), signed into law in 1996, provides that no state has to recognize same sex marriages for any purpose from any other state. That law was required or the Full Faith and Credit clause of Article IV would have required the recognition. Courts have upheld the constitutionality of the DOMA.
Thanks for your reply. I appreciate the information.
I'm wondering how this is administered in practice. There are various things such as insurance, loans, legal liability etc. I have no idea if or how many of these are federal or state. And if someone in the case above moves to Texas and says "married' on a particular form, is the form null and void? Does anyone check?
I can't imagine they turn in their license when they cross the state line. Maybe there's not a simple answer to this; I can imagine great complexity in administering the law...