We compiled distribution data on Ammophila collected in the Grand Canyon ecoregion (GCE) in northern Arizona and southern Utah. We report 35 species occurring from 350 to 2865 m elevation. Three new state records are reported for Arizona and one for Utah. A total of 73.8%–80.5% of the 41 Arizona Ammophila species occur in the GCE, and 16 species were detected in Grand Canyon National Park. Four species in Utah's portion of the GCE are not known to occur in Arizona. Five Ammophila species were frequently captured (A. azteca, A. pruinosa complex, A. breviceps, A. acuta, and A. strenua), whereas most species were relatively infrequently encountered. Four species were detected only at single localities, but no evidence of localized endemism was found. Flight periods generally extended across the growing season, but 4 species appeared to fly in springtime and before the onset of the summer rainy season. Raw species richness was unimodally distributed across elevation, with a peak at 1750 m; however, adjustment of species richness by land area within 100-m elevation belts produced a linear decrease of species density across elevation (R² = 0.733). This pattern indicates conformance to the temperate-to-tropical negative relationship between species richness and latitude. Four species were found only below 1500 m elevation, whereas 5 species were detected at upper elevations, indicating that only 25.7% of the fauna appear to be constrained by elevation. Thus, we report relatively high GCE Ammophila species richness, relatively weak ecotonal impacts on the assemblage along the southern Colorado Plateau geologic province boundary, and modest corridor and barrier/filter landform impacts of Grand Canyon on this genus.