The following 3 reasons suggest that the Canadian dollar might be undervalued against the USD:
The Canadian dollar heavily depends on the price of oil. Regression analysis as well as other interest theory suggests that the Canadian dollar is currently 8% undervalued.
The following chart shows the strong relationship between the Canadian dollar and the price of oil over the last 30 years (from January 1986 through April 2016). The monthly exchange rate data is from the Bank of Canada. The monthly price of oil is from Department of Energy.
related, Victor Adair with Michael Campbell: A Significant Turn In The US Dollar