The advent of hydraulic fracturing lead to a dramatic increase in US oil production. Due to regulatory, shipping and processing constraints, this sudden surge in domestic drilling caused an unprecedented divergence in crude acquisition costs across US refineries. We take advantage of this exogenous shock to input costs to study the nature of competition and the incidence of cost changes in this important industry. We begin by estimating the extent to which US refining’s divergence from global crude markets was passed on to consumers. Using rich microdata, we are able to decompose the effects of firm-specific, market-specific and industry-wide cost shocks on refined product prices. We show that this distinction has important economic and econometric significance, and discuss the implications for prospective policy which would put a price on carbon emissions. The implications of these results for perennial questions about competition in the refining industry are also discussed.