Previous studies have shown that the observed correlation between the age of the lithosphere and rate of ''absolute'' motion of subducting oceanic plates at trenches can be explained by a net slab-pull force derived from a halfspace cooling model for the thermal lithosphere. Rates of motion are proportional to the square root of age. However, depth/age trends suggest that the ''plate'' thermal structure applies to much of the seafloor; rate and age data for trenches where the oldest seafloor is subducted in the western Pacific should reflect the ''plate'' structure. Fitting rate and age data from 16 trenches to net slab-pull models based on both halfspace and plate cooling models shows that rates of plate motion at the five western Pacific trenches where the lithosphere entering the trench is oldest are systematically lower than the rates predicted by the best fitting halfspace model. In contrast, these data do fit a slab-pull model based on plate cooling with R2=0.97, and an RMS error of 4.7 mm/a. Thus the plate model represents a statistically significant improvement over the halfspace model, and the plate-like ''flattening'' of depth/age trends is reflected in the relationship between the rate of subduction and the age of the seafloor at Pacific trenches. ¿ American Geophysical Union 1995