The US Mint has apparently been adding some content to their archives search. In particular I found some press releases from the 1970s containing information which would be hard to locate anywhere else.

The information presented in this section includes a portion of the larger United States Mint Historical Reference Collection. Over time, the information available in the Archives will offer a unique timeline of numismatic history, ranging from the late 18th Century to the present. Some examples of archival materials include legislation, press releases, annual report excerpts, and coin images.