The US economy is in very bad shape -- about a crisis

So, keeping job is top priority, seeking promotion is second priority, finding another job is third priority.

From the info, your boss is willing to promote you, and has been working on that, and has promised to continue working on that -- it did not work, I do not believe the boss just lied and did not do anything, the truth could be: she tried it, but could not have it done with her boss and the company's budget (the company itself may well under pressure, and may be going through budget shrinking and downsizing, bosses don't like to tell these things, they at most will imply something but wouldn't tell clearly). It's not a personal matter, it's totally a business matter. It could be a little bit politics matter, like another dept. got more promotions, in that case it means your boss is not strong enough (but I doubt about it, usually people able to make themselves a boss are very sophisticated, they know how to handle that kind of issues).

I wouldn't take it too serious, I would just say thank you, then quietly look around for other opportunities, if I could not find anything I'll just keep perform my current job, with or without promotion, but if I find something better, I'll just walk away, again, no matter whether promotion happens (unless it's an impressively good one).