Most countries around the world including the United States took actions to control COVID-19 spread that included social distancing, limiting air and ground travel, closing schools, suspending sports leagues, closing factories etc., leading to an abrupt shift in human activity. On-road NO_x emissions from light and heavy duty vehicles decreased by 9% to 19% between February and March at the onset of lockdown in the middle of March in most of the US; between March and April, the on-road NO_x emissions dropped further by 8% to 31% when lockdown measures were the most stringent. These precipitous drops in NO_x emissions correlated well with tropospheric NO₂ column amount observed by Sentinel 5 Precursor TROPOspheric Monitoring Instrument (S5P TROPOMI). Further, the changes in TROPOMI tropospheric NO₂ across the continental U.S. between 2020 and 2019 correlated well with changes in on-road NO_x emissions (r = 0.68) but correlated weakly with changes in emissions from the power plants (r = 0.35). These findings confirm the known knowledge that power plants are no longer a major source of NO₂ in urban areas of the US. With increased unemployment rate in 2020 after the lockdown combined with telework policies across the nation for non-essential workers, the NO₂ values decreased at the rate of 0.8 µmoles/m² decrease per unit percentage increase in unemployment rate. Across the urban regions we found positive correlation between S5P TROPOMI NO₂ and Suomi NPP Visible Infrared Imaging Radiometer Suite (VIIRS) aerosol optical depths indicating common source sectors for NO₂ and aerosols/aerosol precursors.