Adam Storeygard

Assistant Professor of Economics, Tufts University



Farther on down the road: transport costs, trade and urban growth (forthcomingReview of Economic Studies)

Abstract: How does isolation affect the economic activity of cities? Transport costs are widely considered an important barrier to local economic activity but their impact in developing countries is not well-studied. This paper investigates the role of inter-city transport costs in determining the income of sub-Saharan African cities. In particular, focusing on fifteen countries whose largest city is a port, I ask how important access to that city is for the income of hinterland cities. The lack of panel data on both local economic activity and transport costs has prevented rigorous empirical investigation of this question. I fill this gap with two new datasets. Satellite data on lights at night proxy for city economic activity, and new road network data allow me to calculate the shortest route between cities. Cost per unit distance is identified by plausibly exogenous world oil prices. The results show that an oil price increase of the magnitude experienced between 2002 and 2008 induces the income of cities near a major port to increase by 6.6 percent relative to otherwise identical cities one standard deviation farther away. Combined with external estimates, this implies an elasticity of city economic activity with respect to transport costs of -0.25 at that distance. Moreover, the effect differs by the surface of roads between cities. Cities connected to the port by paved roads are chiefly affected by transport costs to the port, while cities connected to the port by unpaved roads are more affected by connections to secondary centers.

Replication data:

Has climate change driven urbanization in Africa? (with Vernon Henderson and Uwe Deichmann; formerly "50 years of urbanization in Africa: Examining the role of climate"; revision requested, Journal of Development Economics)

AbstractThis paper documents strong but differentiated links between climate and urbanization in Sub-Saharan Africa, which has experienced significant moisture reductions. In large panels of districts and cities, we find drier conditions increase both urbanization and total city incomes in places most likely to have an urban industrial base. In this context, migration to cities provides an “escape” from negative agricultural moisture shocks. However, in most places (75% of our sample), local cities just service agriculture and there is no escape into alternative export-based employment. There, drying has little impact on urban population share or total urban income. 

The Global Spatial Distribution of Economic Activity: Nature, History, and the Role of Trade (with Vernon Henderson, Tim Squires and David N. Weil)

AbstractWe study the distribution of economic activity, as proxied by lights at night, across 250,000 grid cells of average area 560 square kilometers. We first document that nearly half of the variation can be explained by a parsimonious set of physical geography attributes.  A full set of country indicators only explains a further 10%. When we divide geographic characteristics into two groups, those primarily important for agriculture and those primarily important for trade, we find that the agriculture variables have relatively more explanatory power in countries that developed early and the trade variables have relatively more in countries that developed late, despite the fact that the latter group of countries are far more dependent on agriculture today.  We explain this apparent puzzle in a model in which two technological shocks occur, one increasing agricultural productivity and the other decreasing transportation costs, and in which agglomeration economies lead to persistence in urban locations. In countries that developed early, structural transformation due to rising agricultural productivity began at a time when transport costs were still relatively high, so urban agglomerations were localized in agricultural regions. When transport costs fell, these local agglomerations persisted. In late-developing countries, transport costs fell well before structural transformation. To exploit urban scale economies, manufacturing agglomerated in relatively few, often coastal, locations. With structural transformation, these initial coastal locations grew, without formation of more cities in the agricultural interior.

Is urbanization in sub-Saharan Africa different?(with Vernon Henderson and Mark Roberts)

Abstract: In the past dozen years, a literature has developed arguing that urbanization has unfolded differently in post-independence sub-Saharan Africa than in the rest of the developing world, with implications for African economic growth overall. While African countries are more urbanized than other countries at comparable levels of income, it is well-recognized that total and sector GDP data are of very low quality, especially in Africa. When viewed from the perspective of effective technology as suggested in endogenous growth frameworks (and as proxied by educational attainment), the African urbanization experience overall matches global patterns. There are differences, however, at a sector level. Agricultural trade price shocks have a differential effect in Africa, but not what is postulated in some of the literature. In our data, shocks that improve farm prices deter African urbanization, as might be expected in simple two sector models. In the remainder of the developing world, such shocks promote urbanization. The paper explores potential reasons for this difference, looking, in particular, at differences in land ownership institutions and the likelihood of agricultural surpluses being invested in urban production. Shocks to modern manufacturing spur urbanization in the rest of the developing world, but effects are dependent on the level of development and implied ability to accommodate the shocks. Thus many countries in Africa, with their lower level of development, do not respond to these shocks. Finally, historical indicators of the potential for good institutions promote urbanization both inside and outside of Africa.


Measuring economic growth from outer space (2012; with Vernon Henderson and David N. Weil), American Economic Review 102(2): 994-1028. (ungated version)

Abstract: We develop a statistical framework to use satellite data on night lights to augment official income growth measures. For countries with poor national income accounts, the optimal estimate of growth is a composite with roughly equal weights on conventionally measured growth and growth predicted from lights. Our estimates differ from official data by up to three percentage points annually. Using lights, empirical analyses of growth need no longer use countries as the unit of analysis; we can measure growth for sub- and supra-national regions. 

Media coverage:
Broadcast: Reuters VideoBloomberg Television
Blogs: The Washington Post: 1 and 2The Wall Street JournalThe New York TimesThe Baltimore SunThe Times [South Africa] Mint on Sunday [India]

Dowry Deaths: response to weather variability in India (2014; with Sheetal Sekhri) Journal of Development Economics 111: 212-223. (ungated version)

AbstractWe examine the effect of rainfall shocks on dowry deaths using data from 583 Indian districts for 2002-2007. We find that a one standard deviation decline in annual rainfall from the local mean increases reported dowry deaths by 7.8 percent. Wet shocks have no apparent effect. We examine patterns of other crimes to investigate if increase in general unrest during economic downturn explains the results but do not find supportive evidence. Women's political representation in the national parliament has no apparent mitigating effect on dowry deaths.

Replication data

Media coverage:
Calcutta Telegraph, Mint [India], The Hindu [India]

Global trends in emerging infectious diseases (2008; with Kate E. Jones, Nikkita G. Patel, Marc A. Levy, Deborah Balk, John L. Gittleman and Peter Daszak), Nature 451: 990-993.

AbstractEmerging infectious diseases (EIDs) are a significant burden on global economies and public health. Their emergence is thought to be driven largely by socio-economic, environmental and ecological factors, but no comparative study has explicitly analysed these linkages to understand global temporal and spatial patterns of EIDs. Here we analyse a database of 335 EID 'events' (origins of EIDs) between 1940 and 2004, and demonstrate non-random global patterns. EID events have risen significantly over time after controlling for reporting bias, with their peak incidence (in the 1980s) concomitant with the HIV pandemic. EID events are dominated by zoonoses (60.3% of EIDs): the majority of these (71.8%) originate in wildlife (for example, severe acute respiratory virus, Ebola virus), and are increasing significantly over time. We find that 54.3% of EID events are caused by bacteria or rickettsia, reflecting a large number of drug-resistant microbes in our database. Our results confirm that EID origins are significantly correlated with socio-economic, environmental and ecological factors, and provide a basis for identifying regions where new EIDs are most likely to originate (emerging disease 'hotspots'). They also reveal a substantial risk of wildlife zoonotic and vector-borne EIDs originating at lower latitudes where reporting effort is low. We conclude that global resources to counter disease emergence are poorly allocated, with the majority of the scientific and surveillance effort focused on countries from where the next important EID is least likely to originate.

Supplementary Information (ungated)

Media coverage:
Broadcast: National Public Radio
Print: NBC NewsThe Times [U. K.]Reuters IndiaU.S. News & World ReportThe Telegraph [U.K.]