TIGER Files and ZIP Codes
Restart Restart ArcMap with the 525_Chinoe_Road map. Zoom to full extent. “X” off the Draw toolbar. Turn off Labels Features. Using Selection > Select By Attributes, find those records in Lex_Roads_2002 in which the ZIPL is not equal (use <>) to the ZIPR. Dismiss the selection window, so you can see the map, with the selected segments. Zoom up on different parts of the map.
What I had planned on showing you, by using this selection, was a clever way to delineate zip code areas. After all, when a street segment has one zip code on one side and another on the other side, the street is obviously a dividing line between the two zip code areas. While you can sort of get an idea of the zip code areas, really what I have shown you instead is how wretched the dataset is. Clearly, the zip code data in this set of TIGER records leaves a lot to be desired. If you want, you may peruse the fields to see what sorts of problems give rise to the unfortunate map, but the main lesson is that there are data sets out there, from reputable sources like the U.S. Bureau of the Census, that are shot through with errors. User beware!
To see the actual zip codes of Lexington, add the shapefile
to the map.20
Increase the outline width of the polygon shapefile to 4.0, make its outline color red and its Fill Color Hollow or No Color. Compare the zip code boundaries with the selected element, which, ...