While using Google, I found a page at the Federal Reserve Bank of St.
Towards the bottom of the page, there are links to each fiscal year's "Annual Report of the Secretary of the Treasury on the State of the Finances." Each report is in its own PDF file, with sizes ranging from under one megabyte to more than 75 megabytes. These annual reports contain the reports of the many departments of the Treasury, including the Bureau of the Mint.
Although some may consider these not as authoritative as the original hand written Mint Reports that are available (?) in some government archive, we all can agree that these are much more accessible. And they might motivate researchers to search the archives for letters and other original materials related to a particular topic of interest.
I am amazed by the large number of books and documents that have become available recently, and look forward to more! Couple these PDF files with some free online OCR programs that convert from image files to text files, and much of the tedious work in bringing the reports to the web as pure text (HTML) files is gone. All that remains is proofreading the text files to fix typos and remove artifacts resulting from stray marks in the PDF images. And, of course, finding the time to proofread.
Never enough time!