Old transcripts for Grad application I thought of applying for master's in US universities in 2011 for fall 2012. So, I had taken official transcripts from my college. But, I didn't apply then.

I'm thinking of applying this year for fall 2014. Can I use the old ones? They were signed with 2011 date on.
In general, a signed, sealed transcript of a completed degree program should always be valid, as there presumably there has not been any changes made to the contents of the transcript since that time.

"Interim" transcripts, of course, would no longer be valid. 

One other thing to note—many schools nowadays want the transcript submitted directly by the university; in such cases, it is unlikely that they would accept a transcript mailed by the student along with the application (if they even accept mailed applications!).