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- In the Contents pane on the left, double-click the Census_2010_By_SuperNeighborhood layer name.
- In the 'Layer Properties' window, in the left column, click the third tab, Source tab.
- At the bottom of the window, click to expand the Spatial Reference section.
- Use the scroll bar on the right to scroll to the bottom of the Spatial Reference section to view the metadata.
Within the Spatial Reference section, notice that the geographic coordinate system is WGS 1984 and that no projected coordinate system is listed. Therefore, the layer is unprojected, meaning the data coordinates are located on the three-dimensional surface of the globe and you can see the Angular Unit is listed as Degrees (or decimal degrees.) Therefore, the Shape_Length field is displaying decimal degrees and the Shape_Area field is displaying square decimal degrees, which is why the numbers are so low. Before measuring distance or area, the data layer should be projected onto a two-dimensional surface. The resulting projection will have a Linear Unit, such as feet or meters. The process of projecting is further covered in the Introduction to Coordinate Systems and Projections course.
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