If iam visiting USA and have a touristvisa and have got 6 months on my I 94. Can I then go to Canada for a week or to whitout losing my I 94 or must I "check out" from USA and do it all over again?
You can exit from the USA for a short visit to a neighboring country, like Canada, and return without changing the status of your I-94. Your original departure date will remain the same as it was before you went to Canada and returned.