USCIS Forms I-539, Application to Extend/Change Non-immigrant visa Status.

Visiting on a B-1/B-2 visa generally allows a stay up to six months in the U.S, with a chance of extension with filing form I-539 for up to six additional months. This would be based upon your filing Form I-539 and getting it approved by United States Citizenship and Immigration Service (USCIS).

For more details visit your nearest immigration office like for example USCIS Vermont Service Center