Canada presents an excellent opportunity to study lithospheric and sublithospheric processes due to its preservation of ~4 billion years of geological history. Deformation from past tectonic processes is preserved in the thick lithosphere of the Canadian Shield, in contrast to the active tectonics and thin lithosphere in the Canadian Cordillera. Such large variations in lithospheric thickness, whether on a sharp or gradual lateral scale, likely perturb mantle convective flow beneath the continent, adding complexity to sublithospheric fabric.We use dispersion data from teleseismic Rayleigh waves to investigate upper-mantle structure beneath Canada and the central-northern USA. For periods of 20 to 220 seconds, azimuthal coverage of inter-station paths is sufficient to resolve isotropic heterogeneities and azimuthal anisotropy across the study area. Significant lateral variation in azimuthal anisotropic parameters and changes as a function of period suggest complex lithospheric and sublithospheric fabric. However, the stratification of the anisotropy is difficult to interpret directly from the phase velocity maps due to the wide depth range sampled by each period.To investigate the depth-dependence of azimuthal anisotropy, we extract the 1D dispersion parameters at selected points in the phase velocity maps. An anisotropic depth inversion is carried out to investigate the relative roles of �frozen� lithospheric fabric and lattice-preferred orientation related to active mantle convective flow. We also search for stratification in azimuthal anisotropy with depth within the thick lithosphere of the Canadian Shield and speculate on the tectonic processes that contribute to such layering.