Various high-frequency (HF) ground-wave propagation models are evaluated by comparing the models' path-loss estimates with field measurements. Multiple sources of ground conductivity and permittivity information and various methods for estimating terrain effects are employed, with the goal of approximating the measured path-loss values as accurately as possible. Estimates are obtained using the Rotheram-Millington spherical-Earth model as well as models that take the path's terrain profile into account, including a simple clearance angle model and more elaborate models estimating knife-edge diffraction loss using the methods of Bullington, Epstein-Peterson, and Deygout. Ground conductivity and permittivity values are obtained from standard ITU conductivity maps or directly measured at the transmit and receive locations. The Google Maps API is used to provide the terrain profile across each link. The resulting improvements in ground-wave path-loss estimation will contribute to more effective communications planning in HF radio networks, and to defining realistic scenarios for simulation studies of MANET protocols and cognitive radio techniques for use at HF.