要旨：地域格差は学術的にも政策的にも旧くて新しいテーマである。戦後日本において国土の均衡発展は一貫した政策目標であったが，2000年代になると世界的な都市間競争を念頭に，規制緩和による都市再生政策が推進されるようになった。一方，現在政府が取り組む地方創生政策は地方圏の経済的疲弊と東京一極集中の是正を通じ人口減少の克服を目指すものであるが，今後その成果の検証が求められよう。地域格差の拡大をめぐって議論がしばしば混乱する理由に，格差現象を把握する概念の不明確さがある。すなわち，人口や所得が地理的に偏って存在することを問題とする「規模の地域間格差」と，人口や世帯あたりで見た所得の差を問題とする「水準の地域間格差」の区別が重要である（豊田,2013）。新古典派経済学の理論によると，労働力の移動が自由であれば，低賃金地域（地方圏）から高賃金地域（大都市圏）へ人口が移動する。その結果，市場の調整メカニズムにより賃金は均衡に向かい「水準の地域間格差」は縮小する。しかし，前者からは人口流出が，後者へは人口流入が生じ，「規模の地域間格差」は拡大する。もし人口移動を制限する政策をとるならば，前者で失業増大，後者では人手不足が生じ，全体の成長が阻害されよう。二つの格差がつねにトレードオフ関係にあるとは限らないが，現実の状況には同時に解決しがたいジレンマが存在する（豊田,2015）。所得の地域格差に関するこれまでの研究では，1993～2008年の都道府県別世帯所得の分析から，所得水準の地域間格差は縮小したが，人口移動が規模の地域間格差を拡大していることを指摘した（豊田,2013）。その後，2008年のリーマンショックや2011年の東日本大震災に伴う深刻な景気の後退を経て，日本経済は緩やかな景気回復過程が続いている。この間，日本社会は人口減少局面への突入，戦後団塊世代の引退，非正規労働者の増加など大きな変化を経験した。本研究では，直近の雇用や所得の地域格差は拡大しているか，それが人口移動にどのような影響を与えているか分析をおこなう。

【国際経済学セミナーと共催】
要旨：International trade and investment flows obey gravity relationships, posing a continuing puzzle. New data on cross-border commercial real-estate investment flows show that they obey gravity, but this relationship is rendered insignificant by controlling for the presence of counterparties from origin countries in destination countries. We attribute this to a strong, robust tendency for preferential matching with same-country counterparties. We set up an equilibrium matching model with a contracting/trust friction affecting different-nationality transactions. The model explains the persistent success of gravity using the friction and the fact that the spatial distribution of same-nationality counterparties is well-explained by historical links between countries.

【国際経済学セミナーと共催】
要旨：We propose and apply a new theory-consistent algorithm, which uses disaggregated inter-city trade data to identify a pyramidic city system with central places and associated hinterlands. Because central places possess more industries than the cities in their hinterlands, and because industries, which are exclusive to central places, are more likely to export to the small, peripheral cities in the central place’s hinterland, we find that aggregate exports from central places to their hinterlands are two to five times larger than predicted by gravity forces. Using a simple decomposition approach, we show that this upward bias results from aggregation along the extensive industry margin, which is why the bias is much smaller and only marginally significant if estimation is conducted in a theory-consistent way at the disaggregated industry level.

要旨：This paper investigates a two-location local public goods economy in which agents choose their residential location and consumption bundles, faced with location-specific disaster risks. The amount of local public goods provision financed by local wealth tax is determined by majority voting of residents to reduce the disaster probability. We show that every equilibrium is wealth stratified if utility functions are constant relative risk aversion with basic consumption in housing. Moreover, when disaster risks in a location increase, population and housing rent decrease and the tax rate increases in that location, while the opposite takes place in the other one. Using this framework, we also evaluate two different policies numerically, namely foreign aid and inter-jurisdiction transfer as a local public good or a lump-sum subsidy. If foreign aid provides local public goods for the riskier location, wealthier agents may move into that location and force poorer agents to move out, making the wealthier agents direct beneficiaries of this foreign subsidy. Furthermore, we find that the inter-jurisdiction transfer from the less risky location to the riskier one may harm the poorer by rising housing rents. Finally, the poorer agents may benefit more from a lump-sum subsidy.

要旨：This paper investigates the impact of high-speed rail on innovative activities of establishments along the rail. Using the case of the opening of Nagano-Hokuriku Shinkansen in Japan, and applying difference-indifferences approach, we estimate the impact of the high-speed rail on the innovative activities along the line. We find that after the opening the high-speed rail, innovative activities by the establishments along the line are significantly increased. Furthermore, collaborative patents across establishments along the line and citations of patents published by the establishments in Tokyo are increased. These imply that the innovative activities along the line is increased through knowledge diffusions from the nearby establishments and those in Tokyo.

要旨：Unlike most of the theoretical researches on economic geography, I assume consumers do not necessarily have access to all the varieties in the market, which motivates firms to compete one another for acquiring customers, and investigate the effects of such competition on economic geography. I first extend the general equilibrium model of monopolistic competition in the closed economy by assuming consumers’ limited access to varieties, and then apply it to the model with two regions. I show (1) the core region enjoys more varieties than the periphery, and (2) economic activities may disperse even at low trade costs when the competition for attention is fierce.

【国際経済学セミナーと共催】
要旨：This paper examines the impact of temperature changes on rural-urban migration using a 56km×56km grid cell level dataset covering the whole world at 10-year frequency during the period 1970-2000. We find that rising temperatures reduce rural-urban migration in poor countries and increase such migration in middle-income countries. These asymmetric migration responses are consistent with a simple model where rural-urban earnings differentials and liquidity constraints interact to determine rural-to-urban migration flows. We also confirm these temperature effects using country-level observations constructed by aggregating the grid cell level data. We project that expected warming in the next century will encourage further urbanization in middle-income countries such as Argentina, but it will slow down urban transition in poor countries like Malawi and Niger.

要旨：This paper investigates unit-level monthly dynamics of housing rents through periods of tenancy and vacancy, using a unique panel of rental units in Tokyo through 1996-2017. We find that (i) consistent overall rent stickiness is attributable to the small extensive margin (limited adjustment opportunity) and small intensive margin (rare adjustment at contract renewal stages); (ii) expanded rent gaps from market level during tenancies become small during vacancies; and (iii) rents exhibit time/state dependence during both tenancies and vacancies, while a specific relationship between a long-term tenant and an owner results in a discount during the tenancy.