State issue Photo ID before boarding airplanes
 

Is it airline regulation or Federal law?

I called the TSA and they say that it isn't federal law (they just check baggage).

I ask because the airlines won't accept the same forms of ID that states use to issue their photo IDs. Further evidence that they are uncooperative ********.

I've heard that its not federal law, but something airlines do to make you feel "safe." I've also heard that if you've forgotten your ID, and you're not an "let me on this plane you're violating my right to travel without ID" asshole, they'll let you on after completing some sort of paperwork.

It is not federal law. It's a combination of both airport and airline rules. To access "secure" areas of an airport you need one (and in most places also a boarding pass). To get into the airlines' "secure" areas you need one.

The TSA does a little more than just check bags as they check people too. But overall, that's about it.

Well when I called the American Air that isn't what they had to say. They said they wouldn't accept any form of ID other than a state issued drivers license or photo ID card.

They refuse to accept all the following (at once):
Birth Certificate
Expired Passport
Social Security card
Valid Student ID card
Expired State issue Photo ID card (expired by two days from time of flight)

The above and proof of residency would be more then enough to get an ID card in any state.