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<DIV STYLE="text-align:Left;"><DIV><P><SPAN>SANDAG uses a Master Geographic Reference File system for storing demographic, economic, and other information. The geographic units in this system (master geographic reference areas, or MGRAs) are very small, defined by census blocks and in some cases sub-block areas. Sub-block areas are formed by overlaying block boundaries to those of other geographic areas such as spheres of influence and community planning areas. Information for non-standard areas such as special districts, service areas, and virtually any user-defined geographic area such as a radius or a drive time from a specific site can be developed by aggregating MGRAs.</SPAN></P></DIV></DIV> |