Abstract: Going beyond the New Economic Geography focus on progress in transportation cost, this paper introduces the dynamic effect of environmental technology on residential location in long-run spatial equilibrium. It develops a model with two regions in which a spatial public good (environmental quality) is degraded by externalities of differentiated private consumption goods, but degradation is abated by those of a single private environmental good. Producing the imperfectly tradable consumption goods requires both mobile workers and immobile workers, while the perfectly tradable environmental good requires only immobile workers. Mobile workers’ location choices are explained by regional disparities in environmental quality and price indexes, rather than in wages. Progress in transportation technology dynamically improves freeness of trade, but progress in environmental technology has the opposite effect. Dispersion occurs when progress in transportation technology dominates, while greater progress in abatement technology may lead to agglomeration.

要旨：This paper develops new theoretical insights into how sectoral trade costs and demand patterns shape specialization and wage levels across locations. It presents two key results. First, locations with stronger demand for sectors with low trade costs command higher wage levels, conditional on productivity and population size. Second, contrary to conventional interpretations, higher wages—rather than larger market size—drive specialization in sectors with high trade costs. This pattern arises not from trade cost savings, but from stronger incentives for firms in low-trade-cost sectors to reduce production costs in order to compete across locations. Existing models have overlooked firms’ strategic incentive to locate production in smaller markets, where trade barriers weaken competitive pressures. These results arise under monopolistic competition and extend to models with perfect competition and external scale economies.

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Abstract: The technical change from steam engines to electric motors dramatically transformed manufacturing activities during the Second Industrial Revolution. This paper explores how this technical change progressed and what consequences it brought for the evolution of economic geography. I hypothesize that electric motors powered by purchased electricity lowered barriers to entry in the manufacturing sector due to their significantly lower fixed costs compared to steam engines. To examine this hypothesis, I exploit the historical expansion of electricity grids in early 20th-century Japan and newly digitized establishment-level official records, including information on power sources of establishments. Descriptive evidence shows that electric motors were widely adopted by establishments of all sizes, whereas steam engines were primarily adopted by large establishments, indicating lower fixed costs of electric motors. Using hydropower potential as an instrument, I document that new entrants played a crucial role in driving this technical change and stimulating manufacturing activities. Overall, these findings lend substantial support for the hypothesis. Furthermore, I find that regions with earlier electricity access experienced substantial population growth throughout the early 20th century and exhibit larger economic activity even in the 21st century. These findings suggest a persistent impact of this technological shock: the rapid increase in entrant activities generated agglomeration forces in manufacturing, with accumulated effects still visible in the spatial distribution of economic activity today.

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Abstract：Existing empirical research in economics on neighborhood racial sorting is overwhelmingly premised on the idea that racial preferences for a location depend on the racial shares in that location, without considering potential spatial spillover effects from nearby areas. Does this matter for the way we view the cross-section and dynamics of racial neighborhood segregation? We nest Schelling (1971)’s bounded neighborhood and spatial proximity theories within a discrete choice model, where the key distinction is precisely such spatial spillovers. We simulate the model and examine the data for 1970-2000 for more than 100 U.S. metros. Two features of the data are most compelling: the powerful presence of racial clusters and the fact that drastic racial change is concentrated at the boundary of these clusters. Both point to the spatial proximity model as the proper foundation for a theory of racial neighborhood evolution. We use these insights to revisit prominent results on racial tipping where our theory guides us to distinguish differences by location. While prior research pointed to powerful racial tipping in the form of White exit, we show this is largely driven by theoretically-distinct “biased white suburbanization” leading to White entry in remote areas. In urban areas far from existing Minority clusters, we find zero or small tipping effects, at odds with a bounded neighborhood interpretation. The most consistent effects of tipping, still of modest size, are found in areas adjacent to existing Minority clusters, confirming the relevance of the racial spillovers of the spatial proximity model. Existing research conflates these quite distinct effects. Overall, our results suggests that tipping is a less central feature of racial neighborhood change than suggested in prior research and that greater attention needs to be paid to spatial dimensions of the problem.

Abstract：(Tentative) We draw on new granular data from cities around the world to study how the spatial distribution of income within cities varies with development. We document that in less-developed countries, average incomes of urban residents decline monotonically in distance to the city center, whereas income-distance gradients are flat or increasing in developed economies. We also show that urban neighborhoods with natural amenities – in hills and near rivers – are poorer than average in lessdeveloped countries and richer than average in developed ones. We hypothesize that these patterns arise due to the differences in the provision of residential and transportation infrastructure within cites. Using a quantitative urban model, we show that observed differences in residential and transportation infrastructure help explain a significant fraction of how the spatial income distribution within cities varies with income per capita.

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Abstract: We explore the impact of public school assignment reforms by building a households’ school choice model with two key features—(1) endogenous residential location choice and (2) opt-out to outside schooling options. Households decide where to live taking into account that locations determine access-to-school—admissions probabilities and commuting distances to schools. Households are heterogeneous both in observed and unobserved characteristics. We estimate the model using administrative data from New York City’s middle school choice system. Variation from a boundary discontinuity design separately identifies preferences for access-to-school from other location amenities. Residential sorting based on access-to-school preference explains 30% of the gap in test scores of schools attended by minority students versus their peers. If households’ residential locations were fixed, a reform that introduces purely lottery-based admissions to schools in lower- and mid-Manhattan would reduce the cross-racial gap by 7%. However, households’ endogenous location choices dampen the effect by half.

【Paper】5/1改訂版　【資料】5/16掲載　【Slide】5/17掲載

Abstract: Knowledge creation either in isolation or joint with another person, using either face to face or internet contact and incorporating internet search ability is analyzed. Both a conceptual phase and a technical phase of research are analyzed, allowing workers to choose endogenously their mode of communication. In addition to formal knowledge, tacit knowledge plays an essential role in the knowledge production process, as it is not internalized. Lead time for face to face communication plays a key role. The sink point is inefficient. Our framework is applied to pandemic restrictions on face to face communication.

【Paper】【Slides】(5/5更新)

Abstract: Urban informality, which is prevalent in Africa’s rapidly growing cities, can reduce private investments, lower tax bases, and exacerbate urban disamenities. A key policy tool to address this problem is greenfield urban planning where governments purchase cheap agricultural land on the urban fringe and partition it into planned, surveyed, and titled de novo plots, which people can purchase and build houses on. Yet, there is very little systematic evidence on the effects of de novo planning choices, such as the size and configuration of residential and non-residential plots. We study the consequences of such planning decisions in Tanzania’s “20,000 plot” project, which provided over 36,000 residential plots in 12 project areas on the fringes of Dar es Salaam in the early 2000s. We study this project using detailed maps, questionnaires, and satellite imagery, and we combine within-neighborhood analysis and spatial regression discontinuity designs. We find that overall, the project secured property rights and access, thus boosting land values, and attracting highly educated owners; small plots, which command higher land values and are built more intensively, are under-provided; access to main paved roads is prized; and development rates are higher where plot layout is more gridded and small plots are bunched together. But planned non-residential amenities are ignored due to low implementation rates and about half the plots are still unbuilt, suggesting that despite the project’s success, significant improvements are possible.