I am a Canadian and I do not have to apply for a B1 visa. However, it is not clear to me how often can I enter USA on this visa. I was planing to go to the states for 6 months (which is the maximum on B1) and then return to Canada for a month and go to the states again for 6 months. Has anyone done this? Is this allowed? Will they grant me the second B1 visa at the border (which is where Canadians get their B1 visas)?