Comice pear trees are self pollinating in places such as the Western United States but in other places they sometimes require help pollinating.
France is where Comice pears are grown mostly and where they originated.
But most Comice pears sold and consumed in the USA are grown in the USA.
Comice Pears originated from France which is why they have a French Name.
However while Comice Pears still grow in France the Comice Pears that we eat and enjoy in the United States are grown in the USA.
The Comice Pears that are bought and sold in the USA are grown in Oregon's Hood River Valley, which is one of the largest pear growing regions.
Oregon has the best climate when it comes to growing pears and most other fruits.
So that is one reason Comice Pears are grown in Oregon.
However you may still be able to grow Comice Pears and other pears in just about any other part of the United States as well.
I've seen pear trees grow pears in Kansas as well so they can be grown just about anywhere.