I downloaded the urban extents grid from GRUMP (alpha).  When opened in ArcGIS, there are only two values 1 and 2.  What do these values mean ?

The alpha version of the urban extent mask does not include attributes. It is just a mask of urban versus rural where 1 = rural, 2 = urban.  Also, -9999 values means “no data”,  -9999 comes from internal “hole” polygons, typically waterbodies.

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