Love wave phase velocity maps provide essential constraints on radial anisotropy and deformation in the crust and upper mantle. However, the phenomenon of overtone interference causes scatter and systematic bias in the velocity measurements and impedes efforts to image small‐scale anisotropic variations. We develop an approach for identifying Love wave measurements that are biased by overtone interference, demonstrate its efficacy with EarthScope USArray data, and determine the first earthquake‐derived Love wave phase velocity maps for the entire conterminous U.S. in the period range 35–75 s. We show that radial anisotropy in parts of the crust and most of the lithospheric mantle is necessary to reconcile these maps with Rayleigh wave phase velocities. Our results convey the impact and geographic variability of overtone interference, offer an easy‐to‐implement method to ameliorate this impact, and present high‐resolution constraints on radial anisotropy beneath North America. Plain Language Summary Measurements of Love wave phase speeds at different frequencies provide unique information that can help understand how the Earth's interior is deforming. These measurements are difficult to make because other seismic waves interfere with the one we are attempting to measure, resulting in low‐quality and biased measurements. Here, we calculate the times at which the different waves arrive and use these times to identify and remove measurements impacted by interference. The resulting cleaned data set increases the precision of derived images of the Earth's interior and reduces bias in these images. Our images suggest shear waves polarized in vertical and horizontal directions are required to have different speeds. Key Points We describe an approach to eliminate overtone interference and improve the quality of Love wave measurements We present the first earthquake‐derived Love wave phase velocity maps of the conterminous U.S., at periods up to and including 75 s Our maps require radial anisotropy in many regions of the crust and upper mantle beneath the U.S.