Sediment thickness plays a key role in understanding earthquake behavior, since thick layers of sediment can slow down seismic waves and increase ground shaking. However, there’s currently no consistent, nationwide map of sediment thickness across the continental U.S.—existing maps are pieced together from regional studies that use different methods. In our study, we used earthquake data to measure how long it takes for seismic waves to travel through sediments and compared those times with known sedimentary regions. From this analysis, we created two new maps of sediment thickness: one based on borehole data (which may underestimate the actual thickness) and another using a seismic velocity model, which provides a more accurate, large-scale view.