What might seem a very small insignificant piece of paper when you first emigrate to your new home in USA is the tiny white piece of paper that gets stamped as you walk through immigration on your way to your American dream... It's called an I94 and this piece of paper determines when you have to leave the country to a "meaningful" destination 2 years from the date that you arrive no matter how long your visa is granted for. You can apply for an extension but this can take up to six months it is easier to leave and have your passport issued with a new I94 giving another 2 years. You can not just pop out to the Caribbean or Mexico it has to be to a different hemisphere. Make sure that this is valid for all members of the family even if the date is not written in the children's I94 the are still under the same rules. An overstay of just one day is frowned upon greatly by the immigration department and with prohibit travel into the country for four years... we nearly got caught out on our children's that weren't stamped with a date... just a word of warning