Lately I've heard more than a few European knitters use the phrase 'American sheep breeds.' Now, granted, I was not a breed-aware knitter during my years living in the US. However, I was based for some time in rural New Hampshire and Maine, and from that era I vaguely remember some sheep talk from local farmers. Something about the idea of these American sheep breeds did not ring true. And so I grew curious.
The breeds I hear referred to as American most commonly, are Corriedale and Cormo - and, to a lesser extent, Rambouillet and Polwarth. So I looked up their origins, and here is what I've learned:
While none of the aforementioned breeds originated in the US, they do have one thing in common: All are cross-breeds between the (originally Spanish) Merino, and some hardier, British long-wool breeds. This cross-breeding was done in order to combine the softness of Merino wool with the comparative hardiness of the long-wool sheep. And it was this that made these new breeds popular imports into the Americas at the turn of the 20th century.
As for their actual origins, here is a brief summary.
The Corriedale breed was developed in Australia and New Zealand, by crossing Merino sheep with Lincoln and Bluefaced Leicester sheep.
The Cormo breed, developed in Australia also, then cross-bred the Corriendale again with Merino.
The Polwarth, also Australian-bred, is similarly a cross of 3/4 Merino and 1/4 Lincoln longwool.
Finally, the Rambouillet is likewise a cross between Spanish Merino and a variety of English longwools. It was developed in France, under Louis XVI. You know those stories of Marie Antoinette getting her own little sheep farm and playing at being a shepherdess dressed up in adorable outfits? Possibly those were the earliest Rambouillets she was playing with!
It is not surprising that these merino-longwool crosses have become popular with American yarn manufacturers and independent hand-spinners. While pure merino yarn is beautifully soft, as we all know it also has some less desirable characteristics, such as pilling. Crossing it with the sturdier longwools can create a yarn that could very be the best of both worlds. These cross-bred sheep would also be easier to raise in harsh climates and landscapes, than the pure Merinos.
This is not to say that there are no American sheep breeds (and if you know of any, please feel free to chime in), only that Corriedale, Cormo, Polwarth, and Rambouillet, are not among them. However, they have certainly been popularised by the US over the past couple of decades. So it's understandable why some mistakenly assume them to be American breeds - just as some assume that Merino originates in Australia and New Zealand.
Sadly, I have yet to try any of these wonderful Merino-Longwool crossbreeds! But I do have some gorgeous Rambouillet yarn from Jill Draper, which I look forward to knitting with, once I am done with my current stack of projects.