Research

Can international trade worsen air quality in places that connect other regions to world markets? I estimate the local pollution effects of the China shock along predicted US freight routes. A historical multimodal network connects US container ports to inland counties, assigning each destination a least-cost gateway and road or rail route. Combining these routes with the growth of Chinese imports yields a transit-exposure index that excludes the county’s own destination demand. In a 2001–2014 county panel, the baseline estimates imply an increase in annual PM2.5 of 0.108 µg/m3, equivalent to approximately 3.2% of the average county-level decline over this period, when moving from the tenth to the ninetieth percentile of exposure growth. The effect remains positive with transport-corridor-by-year fixed effects, conditional on local import competition, input access, and environmental controls. Many highly exposed transit counties have modest direct industrial exposure to Chinese imports. The findings reveal an environmental cost of globalization that extends beyond the places where traded goods are produced or used.

Transport technologies do more than reduce distance: they change which features of geography are economically valuable. I study Japan’s transition from sail to steam and construct county-to-county travel times from historical winds, ocean currents, bathymetry, and Japanese vessel performance. Steam created sharply uneven gains in market access across otherwise connected coastal counties. Places receiving larger predicted gains had adopted modern production technologies more extensively by 1920, expanded their banking presence, and experienced faster population growth thereafter. A one-standard-deviation gain predicts about 11 percent greater population growth by 1930, with little differential growth near the 1890 baseline. The evidence traces a gradual reorganization in which productive technology and financial organization adjusted to a new opportunity landscape while population continued to reallocate.