We obtained estimates of mobile emissions in California from CARB's EMission FACtor (EMFAC) model (version EMFAC 2021 with MPOv11) for calendar years 2000 through 2019 . The EMFAC model uses detailed California-specific data to estimate emissions by year and fleet and has been approved by the US EPA . Estimated emissions were spatially allocated to a 1 km by 1 km grid using surrogates developed by CARB and CARB's Spatial and Temporal Allocator (ESTA) model. The ESTA model uses spatial surrogates that are derived from linklevel traffic measurement data combined with population estimates and spatial information about idling locations, rest stops, and distribution centers . The resulting dataset contained spatially resolved annual total exhaust, evaporative, brake wear, and tire wear emissions for primary PM2.5 and four precursor species: NOx, VOC, NH3, and SOx. EMFAC2021 reports results for 54 vehicle categories and five fuel types (gasoline, diesel, natural gas, plug-in hybrid, and electric).