Branch mint

 
A branch mint is a satellite operation of (usually) a national mint. In many cases it will add a Mint mark to coins that is different from the one that may be used at the main facility, although each country has different rules that may vary over time. Added letters are shown below for the United States, France, and Switzerland. Because of this difference coins produced at branch mints may be worth more or less to collectors than those from the main one, depending on their mintages.
United States.
The original and main Mint of the United States Mint, has been located in Philadelphia (P or no letter), since 1793. Its current facility, Philadelphia's fourth, opened in 1969.
U.S. branch mints have been located at:
Great Britain.
The Royal Mint of the United Kingdom is located at Llantrisant, Wales. It is currently the only facility of the Royal Mint but has had branch mints in the past, located at:
France.
The Monnaie de Paris – the French Mint – is a state-owned industrial and commercial company (EPIC). The current French mint facility is in Paris. There have been numerous French mints in modern times, i.e. since the French Revolution. These mints include cities outside of the traditional French borders as a result of the French Empire and other political events.
Canada.
The Royal Canadian Mint, based in Ottawa, has one branch in Winnipeg, Manitoba. The Ottawa mint was itself a branch mint until the Royal Canadian Mint became independent of the British Royal Mint.
There was also a branch mint at Hull, Quebec, which was opened for a few years.
Switzerland.
The current Swiss mint is located in Bern (B). In the past, Swiss coins were manufactured in Bruxelles/Brussels (B.), Strasbourg (BB) and (AB) and Paris (A). French coins of the First French Empire were made in Geneva. Most of the Swiss Cantons were still producing their own coinage in 1848 when Switzerland re-constituted itself as a Confederation and, in 1850, pegged the newly adopted Swiss franc to the French franc.