Cosmogenic ¹⁰Be exposure ages from moraines in the Wallowa Mountains,Oregon, identify two maximal late Pleistocene glaciations at21.1 ± 0.4 ka and 17.0 ± 0.3 ka and a minor glacialevent at 10.2 ± 0.6 ka. Our new high-resolution chronology,integrated with other well-dated glacial records from the westernUnited States, demonstrates substantial differences in the synopticresponses of western U.S. glaciers to climate forcing associatedwith the global Last Glacial Maximum and subsequent millennial-scaleevents originating in the North Atlantic region. These variablesynoptic glacier responses identify large changes in the relativecontributions of regional to global controls on the climateof the western United States that accompanied the deglaciation.