We quantify the distortionary effects of nexus tax laws on Amazon's distribution network investments between 1999 and 2018. We highlight the role of two features of the expansion of Amazon's network: densification of the network of distribution facilities and vertical integration into package sortation. Densification results in a reduction in the cost of shipping orders, but comes at the expense of higher facility operating costs in more expensive areas and lower scale economies of processing shipments. Nexus laws furthermore generate additional sales tax liabilities as the network grows. Combining data on household spending across online and offline retailers with detailed data on Amazon's distribution network, we quantify these trade‐offs through a static model of demand and a dynamic model of investment. Our results suggest that Amazon's expansion led to significant shipping cost savings and facilitated the realization of aggregate economies of scale. We find that abolishing nexus tax laws in favor of a non‐discriminatory tax policy would induce the company to decentralize its network, lowering its shipping costs. Non‐discriminatory taxation would also entail lower revenue, however, as tax‐inclusive prices would rise, resulting in a fall in profit overall. This drop and the decline in consumer welfare from higher taxes together fall short of the increases in tax revenue and rival profit, suggesting that the abolishment of nexus laws would lead to an increase in total welfare.

We study commodity taxation and characterize the Laffer curve, a trade-off between tax rates and revenue, in noncompetitive markets. Pricing in these markets leads to incomplete tax pass-through and agents re-optimize their purchase and pricing decisions in response to any tax change. We use detailed data from Pennsylvania, a state that monopolizes retail sales of alcoholic beverages, to estimate a model of demand for horizontally differentiated products that ties consumers' demographic characteristics to heterogeneous preferences for spirits. We find that under the state's current tax policy, spirits are overpriced. Distillers respond to decreases in the tax rate by increasing wholesale prices, which limits the state's revenue gain to only 13% of the incremental tax revenue predicted under the common assumption of perfect competition. The strategic response of noncompetitive firms to changes in taxation therefore flattens the Laffer curve significantly.