In this month’s QST magazine there was a reference to an “old” article from May 1994 about the evolution of ham radio call signs in the US from the the beginning (before call signs) to the present. Even though the present is 1994 when the article was written, I think it is the same as it is now. I found it enjoyable to read about the changes throughout the past 100 years.
ARRL members have access to the magazine archives such as QST, etc. The URL of the archives search is http://www.arrl.org/arrl-periodicals-archive-search . The article is titled An Overview of Amateur Call Signs — Past and Present from the May 1994 issue. Once you are logged in, assuming you are an ARRL member, a direct link that should work is http://p1k.arrl.org/pubs_archive/90373 and if not, go to the archive search page and select all the articles from the May 1994 QST issue and page through until you find it. Open the PDF and read it online or print it out.