City directories can be a great genealogical resource because not only can they give your ancestor's name and address, if you use them well, you can even find out information about your ancestor's residences, their occupation, and even possibly when and where they died.
The following video is from the Barefoot Genealogist from Ancestry.com describing how to use city directories effectively.
This video from Ancestry.com also gives some good tips for utilizing city directories.
Need help finding more records? Try our genealogical records directory which has more than 1.3 million sources to help you more easily locate the available records.