The study looked at how a potential customs union between Canada and the U.S. could impact trade, output, and investment in Canada. By using a complex economic model, the researchers found that such a union could boost Canada's GDP by around 1% and increase trade by almost 20%. Industries like transportation equipment, electronics, and machinery would benefit the most, while services and resource-based industries would see smaller gains. The key to these positive outcomes lies in getting rid of certain trade rules.