Sediment thickness is a crucial measure for many seismic studies. The slow seismic velocities associated with thick sedimentary sequences can be problematic when inverting for regional tomographic images of the crust and upper‐mantle structure, and is an essential piece of information for better constraining ground‐motion models as sediments can amplify shaking. Yet there is currently no map of sediment thickness across the conterminous United States that is not a combination of smaller regional studies with potentially inconsistent methodologies. In this work, we measure the delay time of P to S conversions at the sediment–basement interface from a set of teleseismic receiver functions and demonstrate the geographical correlation with known sedimentary provinces. From this, we produce two maps of sediment thickness, using (1) a borehole‐derived empirical relation and (2) the mean velocity in the upper 5 km of a tomographic model. Although the former is likely an underestimate, the latter is an excellent first‐order representation of sediment thickness across the United States.