Abstract1 This paper presents a comprehensive analysis of hilliness effects in American urban communities. Using data from seventeen cities, robust relationships are established between elevation patterns and density and income gradients. We find that high-income households display strong preference for high-altitude, high-unevenness locations, leading to spatial income stratification at both the city and tract-level. We further analyze potential causes of this propensity: micro-climate, crime, congestion, view effects, and use of public transit. We conclude that the role of elevation in urban systems should not be neglected. Multi-dimensional spatial methods are crucial to investigations of cities with substantial unevenness. Redistributive social and economic policies must struggle with a fundamental, topographical dimension to inequality. JEL: J10, R11, R12