The paper "The Greenness of Cities: Carbon Dioxide Emissions and Urban Development" by Edward L. Glaeser and Matthew E. Kahn examines the relationship between urban development and carbon dioxide (CO2) emissions in the United States. The authors analyze CO2 emissions from various sources, including driving, public transit, home heating, and electricity usage, across 66 major metropolitan areas. They find that California has the lowest emissions, while Texas and Oklahoma have the highest. The study also reveals a strong negative correlation between emissions and land use regulations, suggesting that restrictive zoning policies may push new development to areas with higher emissions. Cities generally have lower emissions than suburban areas, with New York being a notable exception due to its older, less efficient infrastructure. The paper concludes by discussing the implications of these findings for urban planning and climate change policy.The paper "The Greenness of Cities: Carbon Dioxide Emissions and Urban Development" by Edward L. Glaeser and Matthew E. Kahn examines the relationship between urban development and carbon dioxide (CO2) emissions in the United States. The authors analyze CO2 emissions from various sources, including driving, public transit, home heating, and electricity usage, across 66 major metropolitan areas. They find that California has the lowest emissions, while Texas and Oklahoma have the highest. The study also reveals a strong negative correlation between emissions and land use regulations, suggesting that restrictive zoning policies may push new development to areas with higher emissions. Cities generally have lower emissions than suburban areas, with New York being a notable exception due to its older, less efficient infrastructure. The paper concludes by discussing the implications of these findings for urban planning and climate change policy.