The story of the liqueur is fascinating.
To start the original manuscript was an alchemist recipe for the elixir of life, it might have been brought back from Constantinople by one of François Annibal d'Estrées ancestor.
Since it seems valuable but he couldn't do anything with it, he brought it to the best herbalists he knew: the cartusian monks.
The monks worked on it for a while but it's only in 1755 that he brother Jerome Maubec managed to refine the recipe to create the first chartreuse "Elixir de Santé". The recipe was written down in a manuscript and kept secret at all cost.
A lot of events happened after that, the monk got expelled and the monastery was seized by the French revolutionaries. They came back few decades later. They created the brand "Chartreuse" in 1840.
In 1903 the monastery and the brand "Chartreuse" was seized by the French government and the monks expelled once again. This time the monks saw the wind turn in advance and moved all the production equipment in Spain to protect it and started the production there. From 1903 the Chartreuse was produced in Tarragona (Spain) by the monk.
At this period the recognition of the liquor grew internationally. In 1925 it appears in the novel "The Magnificent Gatsby".
The monks finally regains the brand after decades of trials and the right to move back their monasteries.
In 1935 a landslide destroyed their facilities at "la Fourvoirie". They saved what they could and moved everything to Voiron, to be close to a train station for logistic. (I have a picture of my great grandfather supervising the transportation of the barrels after the landslide, I can share it if I manage to find it again).
They moved the distillery to Aiguenoire in 2018.
The monks created a company that produce the chartreuse, all the technical steps (bottling, labeling ...) are done by this company under the monks supervision but the recipe is still kept secret and only a few monks have access to it. So, despite the million of bottles produced every year, the critical steps of the recipe, the mix of plants, are still done by the monks themselves in secret.
Chartreuse can be hard to find in the US right now since it grew in popularity since the early 2010s but the monks don't want to increase production. From what I understand their mindset is that there is no point of increasing the production for a trend that might be gone in a few decades.