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U-Pb geochronologic and Hf isotopic analyses have been conducted on detrital zircons extracted from 36 samples of Neoproterozoic through Triassic passive margin strata from western North America. The data serve as an improved reference for comparison with inboard strata that accumulated on the North American craton and outboard strata belonging to potentially displaced Cordilleran terranes. As expected, this reference documents significant variations in ages and Hf isotope compositions both north-south and also through time. The data also provide insights into the provenance of Cordilleran passive margin strata. During Neoproterozoic, Cambrian, and Early–Middle Devonian time, most grains were shed from relatively local basement rocks and from Mesoproterozoic clastic strata containing 1.2–1.0 Ga grains that originated in the Grenville orogen. This pattern was interrupted during Ordovician time …