Social accounting matrix (SAM) models have become standard methods to provide quantitative economic impact evaluation. SAM models and methods have a wide body of literature and dates back several decades. In recent years there has been a growing interest in using interregional and multiregional SAM models. IMPLAN provides data necessary, in a convenient format, to construct single-region SAM models. Procedures of the use of IMPLAN data in concert with BEA’s “journey-to-work” commuting flows and data from the Commodity Flow Survey (CFS) collected by the Census Bureau and compiled by the Bureau of Transportation Statistics to construct state-level multiregional SAM models has been demonstrated. However, little research exists concerning the creation of multiregional SAM models at geographic scales lower than states, especially the roll that interregional trade plays in the accuracy of these models. This paper evaluates sensitivity of multiregional SAM multipliers to the procedures used to estimate interregional trade flows.