I'm traveling for my birthday weekend...is there a currency exchange booth at the train Station?

If you're staying in Niagara Falls NY then America cash is accepted everywhere. However in Niagara Falls Canada you will most likely need both currency as it tends to fluctuate and certain credit cards don't always work over the border. As far as the closest currency exchange I would suggest finding a local bank rather than a mall to get your money exchanged.

There is no currency exchange booth at the station

I'm not sure. Going to Canada now, they take American money. American money is more valuable to them.