Understanding the idea of economic integration may be straightforward, but measuring it is not. The academic literature has identified a wide range of measures that capture various aspects of integration. Of these, the four most frequently used measures are product-level prices, factor markets, trade volumes, and product availability. All four are valuable measures that effectively capture different aspects of economic integration. The differences between the measures suggest that some might be more useful in certain contexts than in others. A comparison between the different measures suggests that the last two might generate the most meaningful insights into North American economic integration because conditions in Mexico, a developing country, are quite different than in Canada and the United States. To motivate the different measures of economic integration, the next section of the paper briefly discusses why economic integration is important. As defined above, economic integration is clearly important for growth, which ultimately determines each country's standard of living. Integration also drives change, which often is difficult and is therefore resisted. These changes directly affect producers and consumers, and therefore it is important to be able to identify the results of measures designed to foster economic integration, like trade agreements. The sections that follow therefore discuss each different measure of integration and what they tell us about integration in North America.