The article explores how European countries coming together in economic and monetary unions have affected their trade relationships. It looks at the connections between the different steps of European integration, like forming a single market and using a single currency, and how these have influenced trade between countries. The researchers found that the process of institutional integration in Europe has had a significant impact on trade integration, with the institutions leading to increased trade between countries. The study suggests that the relationship between these two types of integration is important for understanding how countries trade with each other.