Geographic information system (GIS) has been used in many agricultural research areas. The objective of this paper is to discuss the applications of GIS in mapping optimum adaptation zones of soybean maturity in the USA. Data from State Soybean Variety Trials conducted in 1998-2003 were obtained for 139 locations, and were used to create regional adaptation map using ArcGIS program. To create adaptation areas suited for soybean growth based on data obtained from these locations, an interpolation between the data was completed using three approaches: the Spline and Inverse Distance Weighted methods, and the Kriging method in ArcGIS and the Spatial Analyst extension. Due to the statistical non-significance on the variations between the kridged maturity group contour lines and the splined smoothing maturity groups, the results were combined from both kridging and spline interpolations to produce the improved adaptation zones for soybean maturity. Final generated map indicated that the MG 0 cultivars are adapted best to the region north of latitude 46o N, whereas succeeding groups are adapted further south. Each of the MGs 0-III is adapted best within approximately two degrees latitude covering an area equivalent to 220 km wide from north to south. The zones of adaptation for MGs IV, V and VI are wider than those for the earlier maturing cultivars. Overall, the regions of adaptation for the early-maturing cultivars (MG 0-III) have not changed; however, the adapted zones for MGs IV, V and VI are much broader than previously thought. Groups VII and VIII, which dominated production areas in the South decades ago are now planted on a limited basis.