An interesting fact of this era is that individual owners of silver were allowed to have their metal coined by the Mint into silver and Trade dollars for a small fee. The Act of 1876 demonetized Trade dollars, making then no longer legal tender in the United States but only for export to Asia. This, as you note, resulted in two very large years of production at the San Francisco Mint.
An aside - consider the very high quality of San Francisco Morgan dollars, especially in the early years of production. Now you know why they were capable of that - their experience producing Trade dollars in quantities of 4-5 million per year (when the Philadelphia Mint had reached the quantity of one million Seated dollar coins only twice, and once with Trade dollars) left them the most capable Mint in the country when it came to crown-sized coins.
An aside - consider the very high quality of San Francisco Morgan dollars, especially in the early years of production. Now you know why they were capable of that - their experience producing Trade dollars in quantities of 4-5 million per year (when the Philadelphia Mint had reached the quantity of one million Seated dollar coins only twice, and once with Trade dollars) left them the most capable Mint in the country when it came to crown-sized coins.



















