If I apply for my green card before the h1b expires but don't get a decision before the expiration do I still need to leave the country? My H1B will expire on Jan 21.2014.
You can extend your H-1B visa based on your I-140 once it has been approved. You can remain in the US, if you are able to quickly get another valid nonimmigrant visa status after January 21, 2014. But, returning to your home country will not affect the processing of your I-140.