Here are some places online to find US city directories:
- List of directories on Fold3.com—fee based.
- View the Ancestry.com page and browse–fee based.
- Search at http://books.google.com –free
- try “city state directory year”
- Search at http://www.archive.org– free
- use the advanced search options as above
- Search at http://www.hathitrust.org/ – free
- click on “catalog” and do a title search as above
- Local library websites may have some
- Local or regional genealogical societies may have some
Feel free to enter your favorite search sites for these in the comments.