Green card not received, can i travel?

i entered US in immigrant visa, its been 45 days and i havent got my green card, but i got my social security card and driving licence. Now i need to travel to India, will i be able to travel to india without a green card, if so what will happen whn i return back to US, my Immigrant visa expires end of this month (july 20011). would some help me find these answers