For 170 years, U.S. Cities have followed a hidden law of growth and decline

A study by the Complexity Science Hub analyzed 170 years of economic data from U.S. cities, revealing a consistent pattern in urban growth and transformation. Despite technological revolutions and industrial shifts, cities maintain a stable level of "coherence," meaning their economic activities remain well-integrated even as they diversify and evolve. This coherence governs how cities adapt without losing their economic identity. The research examined 650 million census records and 6 million patents, showing that cities gradually transitioned from manufacturing and craftsmanship to services and engineering. Notably, West Coast cities like Los Angeles and San Francisco, which developed later, experienced rapid diversification following the Gold Rush but maintained coherence levels comparable to older East Coast cities. The findings suggest that urban economic transformations are constrained by the need to preserve coherence, requiring cities to develop new industries in ways that fit their existing economic structures. This insight helps explain how cities like Pittsburgh and Boston successfully reinvented themselves after industrial decline.