currency exchage in Nigara Falls area?

We will go to Falls, Toronot area tomorrow. Just notice that we don't have any Canada dollar yet. :-( I called our bank, they said they don't carry any Canada dollar and it's too late to order now. Could we bring US dollar to Niagra Falls area and exchange at there? Or can we use US dollar in Canada at all? We will use credit cards most of time, but may still need some small bills, right?