I didn't want to just spotlight city directories. I wanted to provide readers with many different options. To find directories online I would go to catalogs and digitized book websites and search on "directory" or "directories" or "women directory" to see what I could find. Sometime I found great sources and other times I didn't find anything that struck me as genealogically relevant.
But what I did find were quite a few directories of directories. These lists provide information about non-city directories that in turn list names, businesses, or other information.
One example is the book, Directories 1930-1931 (Exclusive of City Directories) available from Hathi Trust.
This work is most likely not a comprehensive list of directories but it does include directories arranged by subject for the United States, Canada, and England. In some cases, the directory listed doesn't appear to hold much useful information for family history research. However, there are some very specific directories that could prove to be a gold mine for genealogists.
Once you find a directory you're interested in, Google it. See if it's found on a digitized book website. Try WorldCat to see if it's in a library. There's some great titles here that your female ancestor might be listed in.