Working Papers (unpublished or long versions)

Climate Policy and Inequality in Urban Areas: Beyond Income

with C. Liotta, P. Avner, V. Viguié and S. Hallegatte. World Bank Policy Research Working Paper WPS 10185, September 2022.

Abstract: Opposition to climate policies seems to arise, at least partly, from their effects on inequality. However, so far, the impact of climate policies on inequality has mainly been studied through the lens of income inequality, and their spatial dimension is poorly understood. This paper, using Cape Town, South Africa, as a case study, investigates the impact of a fuel tax on both spatial and income inequalities. It uses a model derived from the standard urban economics land use model, accounting for four income classes and four housing types. This modeling framework allows decomposing the impacts of the tax by income class, housing type, and housing location. The analysis also decomposes the impacts of the tax over different timeframes, assuming that households and developers progressively adapt to the tax. The findings reveal strong evidence that in the short term, there are both income and spatial inequalities, with households being more negatively impacted by the fuel tax if they earn low incomes or live far from employment centers. In the medium and long term, these inequalities persist: the poorest households, living in informal settlements or subsidized housing, have few or no ways to adapt to changes in fuel prices by changing housing type, adjusting their dwelling sizes or locations, or shifting transportation modes. Low-income households living in formal housing also remain impacted by the tax over the long term due to complex effects driven by the competition with richer households on the housing market. Complementary policies promoting a functioning labor market that allows people to change jobs easily, affordable public transportation, or subsidies helping low-income households to rent houses closer to employment centers will be key to enable the social acceptability of climate policies.

Abstract: The paper studies the market failures associated with land tenure insecurity and information asymmetry in an urban land use model, and analyzes households' responses to mitigate tenure insecurity. When buyers and sellers of land plots can pair along trusted kinship lines whereby deception (the non-disclosure of competing claims on a land plot to a buyer) is socially penalized, information asymmetry is attenuated, but overall participation in the land market is reduced. Alternatively, when owners can make land plots secure by paying to register them in a cadaster, both information asymmetry and tenure insecurity are reduced, but the registration cost limits land market participation at the periphery of the city. The paper then compares the overall surpluses under these trust and registration models and under a hybrid version of the model that reflects the context of today's West African cities where both registration and trusted relationships are simultaneously available to residents. The analysis highlights the substitutability of trusted relationships to costly registration and predicts the gradual evolution of economies towards the socially preferable registration system if registration costs can be sufficiently reduced.

Big Data in Transportation: An Economics Perspective

with S. Soumahoro, World Bank Policy Research Working Paper WPS 9308, June 2020.

Abstract: This paper reviews the emerging big data literature applied to urban transportation issues from the perspective of economic research. It provides a typology of big data sources relevant to transportation analyses and describes how these data can be used to measure mobility, associated externalities, and welfare impacts. As an application, it showcases the use of daily traffic conditions data in various developed and developing country cities to estimate the causal impact of stay-at-home orders during the Covid-19 pandemic on traffic congestion in Bogotá, New Dehli, New York, and Paris. In light of the advances in big data analytics, the paper concludes with a discussion on policy opportunities and challenges.

Customary Land Conversion and the Formation of the African City

with P. Picard, World Bank Policy Research Working Paper WPS 9192, March 2020. Revised version here.

Abstract: As cities grow and spatially expand, agricultural land is converted into residential land. In many developing countries, especially in Sub-Saharan Africa, this process is accompanied by a change in land tenure, whereby plots held under traditional customary arrangements are sold to new urban residents, possibly with formal property rights. This paper studies joint land-use and land-tenure conversion in an urban economics model in which intermediaries purchase agricultural land from customary owners and attempt to transform it into residential plots with statutory property rights. The spatial equilibrium includes a mix of land uses and rights where statutory and non-statutory residential plots coexist with customary land that is mainly used for agriculture. Because customary ownership is subject to uncertainty (because of tenure insecurity), the conversion process includes a potential information asymmetry between customary owners and intermediaries. The analysis shows that a market failure may emerge whereby some customary owners prefer to continue farming their land rather than participate in the urban residential land market, which results in a city that is too small. Empirical analysis using Malian data validates the key features of the model captured by land price gradients, as well as the ranking and the variance of land prices, and is suggestive of the presence of information asymmetry.

Assessing Urban Policies Using a Simulation Model with Formal and Informal Housing: Application to Cape Town, South Africa

with B. Pfeiffer, C. Rabe and V. Viguié, World Bank Policy Research Working Paper WPS 8921, June 2019.

Abstract: Building on a two-dimensional discrete version of the standard urban economics land-use model, this paper presents a tractable urban land-use simulation model that is adapted to developing country cities, where formal and informal housing submarkets coexist. The dynamic closed-city framework simulates developers' construction decisions and heterogeneous households' housing and location choices at a distance from various employment subcenters, while accounting at the same time for land-use regulations, natural constraints, exogenous amenities, and dynamic scenarios of urban population growth and of State-driven subsidized housing. Designed and calibrated for Cape Town, the model is used to assess the impact of an urban growth boundary and of changes in the scale of subsidized housing schemes, informing a discussion of the potential trade-offs in policy objectives and of policy effectiveness.

Highway Politics in a Divided Government: Evidence from Mexico

with Souleymane Soumahoro, World Bank Policy Research Working Paper WPS 8710, January 2019.

Abstract: This paper combines local election results and geo-referenced road construction data over 1993-2012 to investigate political bias in road infrastructure investment in a democratic setting, focusing on the case of Mexico. Using a regression discontinuity design, the paper finds strong evidence of partisan allocation of federally-funded highways to municipalities that voted for the president's party in legislative races, nearly doubling the stock of highways compared to opposition municipalities. The extent of political favoritism in highway provision is stronger under divided government when the president has no majority in the legislature, suggesting political efforts to control the Congress.

The informal city

with Lara Tobin, World Bank Policy Research Working Paper WPS 8482, June 2018.

Abstract: This paper proposes a theory of urban land use with endogenous property rights. Socially heterogeneous households compete for where to live in the city and choose the type of property rights they purchase from a land administration which collects fees in inequitable ways. The model generates predictions regarding sorting and spatial patterns of informality consistent with developing country cities. It also highlights non-trivial effects of land administration reforms in the presence of pecuniary externalities, possibly explaining why elites may have an interest in maintaining inequitable land administrations that insulate them from competition for land from the rest of the population.

The globalization of farmland: theory and empirical evidence

with R. Arezki and C. Bogmans, World Bank Policy Research Working Paper WPS 8456, May 2018. Revised version here.

Abstract: This paper is the first to provide both theoretical and empirical evidence of farmland globalization whereby international investors directly acquire large tracts of agricultural land in other countries. A theoretical framework explains the geography of farmland acquisitions as a function of cross-country differences in technology, endowments, trade costs, and land governance. An empirical test of the model using global data on transnational deals shows that international farmland investments are on the aggregate likely motivated by re-exports to investor countries rather than to world markets. This contrasts with traditional foreign direct investment patterns where horizontal as opposed to vertical foreign direct investment dominates.

Roads and the geography of economic activities in Mexico

with Brain Blankespoor, Theophile Bougna and Rafael Garduno-Rivera, World Bank Policy Research Working Paper WPS 8226, October 2017.

Abstract: This paper estimates the impacts of road improvements on local employment and specialization in Mexico for 1986-2014, through changes in access to domestic markets and travel costs to ports and the U.S. border. Instrumenting for road placement endogeneity and addressing the recursion problem in regressions that involve access to markets, the analysis finds significant and positive causal effects of improved domestic accessibility on employment and specialization. It also finds that employment is stimulated by lower transport costs to the U.S. border, but harmed by lower transport costs to ports. Heterogeneous effects are found across sectors and regions.

Rural-urban migration in developing countries: a survey of theoretical predictions and empirical findings

with Somik Lall and Zmarak Shalizi, World Bank Policy Research Working Paper WPS 3915, May 2006.

Abstract: The migration of labor from rural to urban areas is an important part of the urbanization process in developing countries. Even though it has been the focus of abundant research over the past five decades, some key policy questions have not found clear answers yet. To what extent is internal migration a desirable phenomenon and under what circumstances? Should governments intervene and, if so, with what types of interventions? What should be their policy objectives? To shed light on these important issues, the authors survey the existing theoretical models and their conflicting policy implications and discuss the policies that may be justified based on recent relevant empirical studies. A key limitation is that much of the empirical literature does not provide structural tests of the theoretical models, but only provides partial findings that can support or invalidate intuitions and in that sense, support or invalidate the policy implications of the models. The authors' broad assessment of the literature is that migration can be beneficial or at least be turned into a beneficial phenomenon so that in general migration restrictions are not desirable. They also identify some data issues and research topics which merit further investigation.

Abstract: In this paper, we investigate how residential segregation and bad physical access to jobs contribute to urban unemployment in the Paris region. We first survey the general mechanisms according to which residential segregation and spatial mismatch can have adverse labour-market outcomes. We then discuss the extent of the problem with the help of relevant descriptive statistics computed from the 1999 Census of the Population and from the 2000 General Transport Survey. Finally, we estimate the effect of indices of segregation computed at the neighbourhood and municipality levels, as well as job accessibility indices on the labour-market transitions out of unemployment using the 1990-2002 Labour Force Survey. Our results show that neighbourhood segregation is a key factor that prevents unemployed workers from finding a job. These results are robust to potential location endogeneity biases.