Question about the N. American Union

I was reading about the proposed North American Union. From what I gather, this would make the US, Canada, and Mexico a borderless union with a shared currency. I have already heard from many US citizens that this would ruin the US and Canadian economy, due to carrying Mexico's financial problems. I would like to know what the Canadian and Mexican members of this forum think about this proposal. Do you see this as a good idea, or another semi-civil war fifty years down the road? Just for the record "Amero" is a terrible name for the currency. Sounds just as generic as the idea.