my wife is going for a tourist visa to US in a couple of weeks. i have a question assuming she gets a stamp which is good for a year or so (my freind got one for 10 years). When she enters the US, she will probably get a stamp for 90 days. if she wants to extend her stay, can she do a visa run to say mexico or canada or does she have to come back to thailand?

thanks, steve

i just found the answer i think at http://www.immihelp.com/visas/extend.html

You can not go to neighboring countries(Canada, Mexico) either by air or road, and come back to get new I-94 and therefore avoid lengthy process of applying for extension. New I-94 will NOT be given. You can't even go to neighboring islands such as Bahamas etc and come back to get new I-94. You will have to actually travel outside of North America and come back.

however, i guess it is possible to extend while in US

Many individuals who come to United States on visitor visa would like to extend their visa. They can apply for extension of stay in US. The extension may granted or not granted depending upon the reason for extension, and whether the USCIS is convinced that the applicant does intend to return to his/her home country after the temporary stay in US.