About the site
A yarn can be on the list if it was milled in the US and/or the fiber is from animals raised in the US. Although I cannot imagine a yarn that is from a US animal but not milled in the US. That would be interesting!
The two statuses
US Milled: the yarn was spun at a mill in the United States.
American Fiber: the fiber is from animals raised in the United States.
Where the notes come from
I look on the producer's website and if it's listed there then it's good enough for me. Sometimes I cannot find the answer and I'll leave it off. It's not a perfect system and I wish I could verify all the entries. I'm trying my best. Feel free to reach out if you have any details.
The idea of this site is to just be a collection from across the internet.
Credits
Yarn weight symbols: Craft Yarn Council's www.YarnStandards.com.