Sheep ranching came in to the Rawlins & Ft. Steele area in the 1880's with I.C. Miller being one of the earliest. He owned the first flock in 1875. In 1882, about 16 large sheep outfits were listed in the Rawlins area and numbers rapidly grew.
The Cosgriff Brothers of Ft. Steele & Rawlins, WY were one of the largest sheep firms in Wyoming, who at the peak of their career ran 125,000 head of sheep in addition to their mercantile & banking interests. Their flocks ranged across most of southern Wyoming from the Encampment area to Rock Springs. Their pioneer mercantile finally extended as far west as Salt Lake City, UT. In 1903 they had one of the single largest shearing plants in the state of Wyoming at Fort Steele; it employed 30 American and 30 Mexican shearers. In 1905 they shipped the largest single shipment of wool from Wyoming by special train from Fort Steele. WY to Boston, MA; it was 800,000 pounds of wool. One of the Cosgriff Bros, James, also owned the Cow Creek Outfit west of Saratoga, WY.
In the spring of 1892, L.W. Vivion went into partnership with George Ferris in sheep production. Six years later they dissolved the partnership and each had clear title to forty-four hundred sheep. In 1915 after the deaths of Thomas & John Cosgriff, Vivion purchased the Cosgriff Bros holdings south & east of Rawlins except for a parcel of land that was sold to Producers & Refiners Oil Corporation which is now the Sinclair Oil Refinery and the Town of Sinclair - formally Parco. The Leo Sheep Company later moved most of its shearing & shipping operations to Wolcott further east on the Union Pacific Rail Road where Vern & Della Vivion were able to get the sheep & shearing barns on the National Historic Register in recent times.