The Universal Soil Loss Equation (USLE) computes the average soil loss per unit area. Many sources in the literature we surveyed give Wischmeier, et. al. (1965) the credit for the development of the USLE. However, Wischmeier’s paper mentions the National Runoff and Soil Loss Data Center and Purdue University for developing it in 1954. A later revision called the RUSLE was prompted by limitations in the older USLE.