This paper presents findings from a critical review and an analytical study of soil stiffness values for the load rating of reinforced concrete box culverts. The responses of the soil-culvert system under dead and live loads were examined separately for a production-simplified, two-dimensional, linear elastic, soil-structure interaction model. First, soil-culvert systems were analyzed to determine dead-load-induced moments in the structure. The results were compared with moments obtained from an AASHTO policy-based structural-frame model and a calibrated value of static soil modulus, E = 10 ksi was selected as the optimum. A comprehensive literature review evaluated reasonable soil stiffnesses for live load analysis in culvert load rating. Typical resilient moduli of 12, 24 and 36 ksi for low, medium and high-quality culvert backfill soils were identified for live load predictions in the soil-structure interaction model.