Yes, Niagara Falls (on both the American and Canadian sides) widely accepts U.S. dollars. Since the falls are a major international tourist destination straddling the border, businesses on the Canadian side (Ontario) are very accustomed to American visitors and will almost always accept U.S. cash. However, there are two important caveats. First, you will almost certainly receive your change in Canadian dollars, and the exchange rate offered by shops and restaurants is usually "convenience-based," meaning it is much less favorable than the official bank rate. Second, while cash is accepted, it is far more economical and common to use a credit or debit card with no foreign transaction fees, as this ensures you get the real-time interbank exchange rate. In 2026, contactless payment is the standard in Canada, even for small purchases like ice cream or parking. On the American side (New York), Canadian currency is occasionally accepted in some tourist shops, but it is much less common, so Canadian visitors should rely on cards or carry U.S. currency when crossing the Rainbow Bridge into the United States.