If you are a tourist visiting the U.S. on a visa, you can stay longer than the initial date granted. For more time to see amber waves of grain and purple mountain majesty, be sure that you qualify.
Just to be clear
According to the U.S. Department of State, getting a b2 visa does not guarantee access into the U.S. It does allow you to travel to a U.S. port of entry and then request permission to enter the country. Once in port, the Department of Homeland Security U.S. Customs and Border Protection (CBP) officials make the call on whether you have permission to proceed beyond the airport or seaport.They may permit or deny access as well as determine the length of your stay. The stamp made on your I-94 document will indicate the date by which you must depart. Be sure to keep this document in your passport and with you at all times.
So you’ve already been admitted into the country and your date to leave is fast approaching. You can apply for an extended visit by filling out Form I-539, Application to Extend/Change Nonimmigrant Status, but it must be done before the date arrives. If you do not apply prior to your I-94 expiration, you could be deported. U.S. Citizenship and Immigration Services (USCIS) recommends you apply 45 days in advanced.
You may only apply for more time to spend in the U.S. if you meet the following requirements as stated by USCIS: You were lawfully admitted into the United States with a nonimmigrant visa; Your nonimmigrant visa status remains valid; You have not committed any crimes that make you ineligible for a visa; You have not violated the conditions of your admission; Your passport is valid and will remain valid for the duration of your stay. If all those statements are true, you may apply for an extended stay.
You may not apply if you were admitted into the country in any of the following categories: Visa Waiver Program; In transit through the United States; In transit through the United States without a visa; Fiance of a U.S. citizen or dependent of a fiance; Informant on terrorism or organized crime.