Megacity growth in the developing world is fueled by a desire to access their large local labor markets. Growing megacities suffer from high levels of traffic congestion and pollution, which degrade local quality of life. Transportation technology that allows individuals to access the megacity without living within its boundaries offers potentially large social benefits, because individuals can enjoy the benefits of urban agglomeration while not paying megacity real estate rents and suffering from the city’s social costs. This paper presents evidence supporting the claim that China’s bullet trains are playing this role. The bullet train is regarded as one of the most significant technological breakthroughs in passenger transportation developed in the second half of the 20th century. Starting in 2007, China has introduced several new bullet trains that connect megacities such as Beijing, Shanghai, and Guangzhou with nearby cities. Through facilitating market integration, bullet trains will stimulate the development of second- and third-tier cities. By offering households and firms a larger menu of location alternatives, bullet trains help to protect the quality of life of the growing urban population. We document that this transport innovation is associated with rising real estate prices in the nearby secondary cities.

Areas differ in their propensity to experience natural disasters. Exposure to disaster risks can be reduced either through migration (i.e., self-protection) or through public infrastructure investment (e.g., building seawalls). Using migration data from the 1920s and 1930s, this paper studies how the population responded to disaster shocks in an era of minimal public investment. We find that, on net, young men move away from areas hit by tornados but are attracted to areas experiencing floods. Early efforts to protect against future flooding, especially during the New Deal era of the late 1930s, may have counteracted an individual migration response.

China urbanization is associated with both increases in per capita income and greenhouse gas emissions. This article uses micro data to rank 74 major Chinese cities with respect to their household carbon footprint. We find that the ‘greenest’ cities based on this criterion are Huaian and Suqian while the ‘dirtiest’ cities are Daqing and Mudanjiang. Even in the dirtiest city (Daqing), a standardized household produces only one-fifth of the emissions produced in America’s greenest city (San Diego). We find that the average January temperature is strongly negatively correlated with a city’s household carbon footprint, which suggests that current regional economic development policies that bolster the growth of China’s northeastern cities are likely to increase residential carbon emissions. We use our city-specific income elasticity estimates to predict the growth of carbon emissions in China’s cities.