I just saw this posting, I wanted to share my experience. If the person applying for rehabilitation is an American citizen, they can apply at most land points of entry. This is what I did for my wife. We just completed the application and supporting docs, drove down the road to our nearest major border crossing (we live in Maine), handed the border agent the application, paid the fee and left. This is not a well known method for processing these apps, so the turnover is fast, she got her approval and rehabilitation in a few days via email and later via post. I would suggest going to a larger border crossing (they must have immigration officer, the tiny ones generally don't), but not a crazy busy one like Detroit/Windsor). We did ours at the Houlton/Woodstock border crossing. This is a much faster option for US citizens.