An article and a research paper that explore the life and death nature of urban density have been added to the Research Center best practices database.
This 2011 article from Economic Commentary, which is published by the Research Department of the Federal Reserve Bank of Cleveland, explores the population density of urban cores. and suggests there are reasons to think that loss of population density at the core of the city could be particularly damaging to productivity and therefore the potential for productivity gains from policies aimed at reversing that trend.
This 2011 report from the University of California, Berkeley, Institute of Transportation Studies, investigates the relationship between transit and urban densities in the United States. The researchers' analysis suggests that light-rail systems need around 30 people per gross acre around stations and heavy rail systems need 50 percent higher densities than this to place them in the top one-quarter of cost-effective rail investments in the U.S. The ridership gains from such increases, the research showed, would be substantial, especially when jobs are concentrated within a quarter-mile of a station and housing within a half mile.