Have you ever wanted to take a peek at IMPLAN’s Trade Flow data? Have you been curious about the details of IMPLAN's Gravity Model?
IMPLAN’s domestic Trade Flow data set consists of county-to-county dollar values of domestic trade in all IMPLAN Commodities (including services). The data are estimated via a doubly-constrained gravity model. The trade captured by this dataset is for both intermediate and final uses, and includes trade within a county (a county to itself). Cool right?
The gravity model was originally adapted from Newton’s Law of Gravity! This law states that the attraction between two masses is directly related to the size of the masses and inversely related to the distance between them. The gravity model was first suggested in an I-O context in Leontief and Strout (1963). In the last fifty years, the gravity model has been widely used to predict trade flows (Federal Highway Administration, 1977, p. 118; Anderson and van Wincoop, 2003; Anderson, 2011).
In 2005, IMPLAN, in concert with the U.S. Forest Service, developed a sophisticated doubly-constrained (until all supplies go somewhere and all demands are fulfilled) gravity model to estimate trade flows for all IMPLAN Commodities between all counties in the U.S. These Trade Flows show the movement of goods and services between and within counties or user-defined regions made up of counties.
Each year, the IMPLAN database is used to estimate the attracting masses (supply and demand) for each U.S. county and each Commodity. These county masses are combined with distances (cost of transport indexes) between and within counties by mode of transport from Oak Ridge National Laboratory’s (ORNL) Transportation Network. The model is calibrated using distances traveled by Commodity from the most recent Commodity Flow Survey (CFS).
A key aspect of the dataset is that the trade is on an origin-of-production basis, not an origin-of-movement basis. This means that the data set tracks from where a Commodity is produced to where it is consumed; as either an intermediate or final use rather than from where a Commodity begins its export journey.
Data on foreign trade can be found in the Commodity Data section.
Written December 19, 2020