After I posted about wanting some light reading yesterday, I spent several hours on the internet researching series books from the 1960s and earlier. The good news is that there are companies reprinting many of these books. I found several interesting sites that list information about these books, including titles, author biographies, and things to look for as a collector. I discovered several authors that I didn't know about before. The bad news is that very few of these books are available at my local library. I could buy them, but I am not one who buys many books.
Anyway, here are a few links in case you are interested:
The Cherry Ames Page: One of the more popular nurse series.
Carlytown: This page is about modern books but she does have a section called the Malt Shop where she talks about books from the 1950s.
The Abbey Girls: A series whose first book was released in 1914 and continued to cover the lives of the original characters' children.
Image Cascade Publishing: A company that is reprinting many of the series from the 1940s - 1960s. Even if you don't buy from them, the site is a good place to find complete series title lists and see the original cover art.