Local zoning boards and planning agencies have almost complete discretion over what gets built where, and they are under intense political pressure from homeowners’ associations and other groups to block development in high-priced, low-density areas for cultural and economic reasons. Culturally, homeowners clamor to preserve what they regard as the “character” of their communities, by which they mean things like traffic, the race and social status of their neighbors, and environmental amenities like green space and scenic views. Additionally, homeowners have strong economic interests in restricting the supply of housing in their neighborhood for two reasons: having more people, especially people with young children, requires a higher tax rate on property, and even more fundamentally, greater housing supply in their neighborhood lowers the value of their unit relative to the prevailing scarcity. Thus, even as housing prices increased, U.S. population density actually fell from 2000 to 2010 for metropolitan area residents as newer housing units were pushed further out into the distant suburbs (Page 99).