working papers

1. A dynamic spatial knowledge economy (JMP)

   Cities have long been thought to drive economic growth. Despite this, analyses of spatial policies have largely ignored the effects of such policies on growth. In this paper, I develop a spatial endogenous growth model in which heterogeneous agents make forward-looking migration decisions and human capital investments over the life cycle. Local externalities in the human capital investment technology drive both agglomeration and growth. I show that, along a balanced growth path, the growth rate depends on the spatial distribution of human capital, making it sensitive to spatial policies. I calibrate the model to data on U.S. metropolitan areas and show that it can rationalize the faster wage growth of workers in big cities, as well as other key patterns in life-cycle wage profiles, migration decisions, and city characteristics. Because workers accumulate human capital at different rates depending on where they live, the model provides an environment in which spatial policy can not just attract skilled workers, but produce them, too. I find that policies that further concentrate skilled workers in large cities are growth-enhancing.

2. Agriculture, trade, and global water use (w/ T. Carleton and I. Nath)

   This paper examines the consequences of international trade for long-run water resources and agricultural productivity. We use a large collection of global spatial data to show that---despite the widespread market failure caused by open access to water as an input with no market price---water-intensive agricultural activity is highly concentrated in water abundant locations, with few exceptions. We use a dynamic spatial equilibrium model of agricultural trade and water resources to quantify the policy consequences of this fact. Model counterfactuals show that international trade in agriculture prevents severe depletion of global water resources and accompanying long-run productivity declines, especially in dry places, by enabling specialization to follow comparative advantage. However, some observed trade liberalization episodes worsen depletion by exacerbating existing inefficiencies.

publications

1. Is the world running out of fresh water? (w/ T. Carleton and I. Nath),
   2024, AEA Papers & Proceedings, 114:31–35
   The quantity of water within Earth and its atmosphere is fixed over time, but water available for human consumption evolves dynamically. We use globally comprehensive geospatial data to establish stylized facts about recent changes in global water resources and their potential implications for human welfare. We show that the net change in water volume on arable lands—which account for 90% of human water consumption—is almost exactly zero. Rapid water loss is concentrated in regions with large populations, low existing water resources, and low agronomic potential. Incorporating trade data shows that water-scarce regions are net importers of water-intensive goods.

work in progress

1. Skills, sorting, and optimal dynamic spatial policy

   I study optimal spatial policies in a quantitative dynamic spatial model with forward-looking migration decisions, human capital investments, and local human capital spillovers.

2. Spatial sources of lifetime inequality

   Wage levels and growth vary across locations. How important is this for explaining patterns in lifetime inequality? Risky human capital model with migration and spatial externalities.

3. Slowdown, divergence, and the geography of human capital accumulation

   A (potentially) unified story of the aggregate growth slowdown, regional growth and decline, and micro evidence on migration and human capital investment.

4. Agriculture and the gains from trade (w/ S. Kortum and I. Nath)

   Does trade matter more for poor countries? New ACR-like welfare formula with nonhomothetic preferences + sector-specific trade and income elasticities.

5. Does eating local reduce emissions? (w/ I. Nath, M. Quentel, and J. Sayre)

   Detailed data on emissions from shipping + emissions from agricultural production (by commodity and location) with a quantitative trade model.

6. Trade policy and food security (w/ I. Nath, A. Schmitz, and S. Stewart)

   You’re a policymaker worried about your nation’s food security in an uncertain, global economy — your people can’t eat manufactures, after all. What trade policies, if any, should you set?