This polygon shapefile contains superdistrict boundaries and population statistics created by the Metropolitan Transportation Comission (MTC) using Census 1990 data. Superdistricts are used in the analysis of sub-county level demographic and travel forecasts. MTC maintains a set of regional travel analysis zones for use in MTC planning studies. These travel analysis zones (TAZs) are typically small area neighborhoods or communities that serve as the smallest geographic basis for travel demand model forecasting systems. From time to time, MTC updates the regional travel analysis zone system to reflect changes in decennial census geography, changes in computing capability, and forecasting needs for particular corridor studies. In addition to regional TAZs and counties, MTC supports an intermediate geographic scale, "superdistricts," for analysis and reporting purposes. There are 34 superdistricts in the nine-county Bay Area. This layer is part of the Bay Area Metropolitan Transportation Commission (MTC) GIS Maps and Data collection. This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.