There is debate concerning the spatial extent and magnitude of the recently identified 1500 yr climate oscillation. Existing evidence is largely restricted to the North Atlantic and adjacent landmasses. The spatial extent, magnitude, and effects of these climate variations within the terrestrial environment during the Holocene have not been established. We show that millennial-scale climate variability caused changes in vegetation communities across all of North America with a periodicity of 1650 ± 500 yr during the past 14 000 calendar years (cal yr). Times of major transitions identified in pollen records occurred at 600, 1650, 2850, 4030, 6700, 8100, 10 190, 12 900, and 13 800 cal yr B.P., consistent with ice and marine records. We suggest that North Atlantic millennial-scale climate variability is associated with rearrangements of the atmospheric circulation with far-reaching influences on the climate.