In this paper, some useful features are extracted from voltage signals measured at one terminal of the transmission line, which are highly efficient for accurate fault locating. These features are the amplitude of harmonic components, which are extracted after fault inception through applying discrete Fourier transform on one cycle of three-phase voltage signals and then are normalized by a transformation. In this paper, the location of single-line-to-ground faults as the most probable type of fault in the transmission networks is considered. The SLG fault locator, which is designed based on the simple algorithm of k-nearest neighbor (k-NN) in regression mode, estimates the location of fault related to the new input pattern based on existing available patterns. The proposed approach only needs the measured data from one terminal; hence, data communication between both ends of the line and synchronization are not required. In addition, current signals are not used; therefore, the proposed approach is immune against current-transformer saturation and its related errors. Tests conducted on an untransposed transmission line indicate that the proposed fault locator has accurate performance despite simultaneous changes in fault location, fault inception angle, fault resistance, and magnitude and direction of load current.