Big cities fuel inequality within and across generations.

Urbanization has long fueled a dual narrative: cities are heralded as sources of economic dynamism and wealth creation yet criticized for fostering inequality and a range of social challenges. This paper addresses this tension using a multidisciplinary approach, combining social sciences methods with satellite imagery-based spatial pattern analysis to study the US urban expansion over the past century. We examine the impact of physical urban spatial characteristics (size, population density, and connectedness) on equality of opportunity, measured through intergenerational mobility, as well as its association with levels of income, wealth, and social capital. Our findings confirm that contemporary cities, particularly population-dense and expansive ones, are indeed divisive forces-acting as centers for income and wealth generation but failing to deliver equal opportunities for economic mobility. Perhaps surprisingly, this polarizing dynamic is a recent phenomenon. In the past, the most urbanized regions performed well in terms of income creation