See attached link.http://search.ancestry.com/search/db.aspx?dbid=2469
On the right side you can locate/browse city directories by location. Then a drop-down box shows the years available.
The search function is not great, but better than it used to be. I just search with last name and city/state and range of years. I suggest that you don't include first names in your search because they are often abbreviated or just initials in the actual city directories. Once you get to the page with the correct surname, you can usually find your person from there.