As the dominant economic geography of America, metropolitan statistical areas largely determine our success as a nation. These groups of counties with a large central core account for 88.6 percent of jobs, 89.1 percent of wages and 90.0 percent of Gross Domestic Product (GDP). Further, metropolitan statistical areas account for the bulk of innovation such as research and development and patenting activity. Understanding the mechanisms underpinning the growth of top-performing metropolitan areas, and sharing best practices, could assist other communities in boosting their economic fortunes. The Most Dynamic Metropolitan Index, ranking 379 metropolitan areas, seeks to provide an objective measure of the economic vibrancy of communities where the lion’s share of Americans work and live.