Abstract:In U.S. states, as in most of the world, mitigation of the spread of COVID-19 was implemented by cities, counties, and governors’ offices through “shelter-in-place” (SIP) and “stay-at-home” orders and related actions (e.g., closure of non-essential businesses). There were several important impacts of government SIP orders on traffic volumes, which in turn had impacts on fuel use and greenhouse gas (GHG) emissions. In this chapter, I estimate GHG emissions and fuel tax revenue at the state and nation scales before, during, and after the SIP guidance. I find that due to approximately 50% reductions in estimated vehicle-miles traveled, U.S. GHG emissions that cause climate change were reduced by 4% in total and by 13% from transportation in the eight weeks after the SIP orders went into effect. This reduction put the United States on track to meet its annual goals for GHG reduction under the Paris Climate Accord. I also calculated that the rapid decline in travel resulted in savings of $5 billion/week to U.S. drivers and a loss of $0.7 billion/week in tax revenue to the states. These consequences should feature in future transportation and climate planning as important variables that may stochastically appear, and which are beyond the influence of transportation agencies.