20211018 10434600 1.0 TRUE RD_MAJOR_SG NOT STATE HWY Data from a number of sources is used for the development and ongoing maintenance of the MajorRoads feature class. Source data includes SanGIS Roads_All, Caltrans State Highway Centerlines, and street centerline data from the County of Imperial. Regional aerial imagery (1'/pixel resolution or better) is generally used as a guide for delineating roadway alignments, primarily using heads up digitizing methods, using ArcGIS desktop software. SANDAG Technical Services - GIS