Go through your results for flights to International Falls in USA with Netflights. Although KLM usually has the best prices, it's best to double check what's available for your travel dates.
Flexible on dates? Conducting your search by month allows you to compare prices to International Falls throughout the year. Accommodation prices will also be higher at this time of year.
So, if the flights to International Falls don't work for you, you could always try searching for flights to other airports in USA.
For even more options, check what other airports you could fly to International Falls from. You might be able to make a saving by going from a different airport or city.