Access to affordable and quality housing for all residents is crucial to sustainability of cities but is increasingly a challenge. Most American cities are severely segregated by race, income, and quality of urban services and infrastructure, to name a few. Some cities are increasingly unaffordable to large segments of population leading to longer travel distances and worsening congestion and air quality. In some parts of the world, especially developing countries, many urban residents live in informal settlements which have negative effects not just on the quality of life and opportunities, but also public health and mortality. Populations in the world living under such environmental conditions are more vulnerable to extreme events.