The Hat Ranch, begun around 1890 by the partnership of Andrew B. (Sug) Robertson and Winfield Scott, was based in Colorado City, Mitchell County. Sometime before 1890 Robertson and Winfield registered the brand, which was made with a half circle over a bar, thus resembling a hat. During the next five years the partners bought out several large ranches, including that of the McKenzie brothers in New Mexico and the 3R and SC ranches, cattle, and horses of the Brunson brothers in Texas. In addition they purchased several thousand 9K cows in Van Horn County and moved them to the newly acquired range. By 1896 more than 50,000 cattle bore the Hat brand on a range area of over 100 square miles, extending from about six miles east of the site of present Seminole in Gaines County to the vicinity of Carlsbad in Eddy County, New Mexico.
Since there was no surface water in the entire area, Robertson and Scott spent $50,000 watering the range. An average of forty men per year was required to operate this immense estate, which at its peak covered nearly a million acres of bought or leased land. As many as 500 saddle horses were used. The main ranch headquarters was located at Monument Springs, New Mexico, and eight smaller division headquarters were established at various points. Robertson appointed his brother R. P. (Dick) manager of this huge operation and instituted a monthly system of reports. Later, when the Robertsons started investing in other Texas ranchlands, that job was turned over to Ed Ramsey. The Hat Ranch became noted for its first-rate cowhands and range cook.
After the turn of the century, the public lands included in the Hat Ranch, particularly those in New Mexico, were gradually abandoned by Robertson and Scott because of the rapid influx of settlers to the area. The decision was made to lease no more land on the Texas side of the line after 1901, since much of this school land was put on the market to homesteaders in four-section blocks. In 1903 the partners leased choice pasturelands in Dawson County, Montana, about 100 miles north of Miles City, to which they shipped 8,000 cattle that spring. They continued these shipments until 1905, when most of the Hat herd had been transported to the northern ranges. Other remnants of the herd were driven to Scott's properties near Stanton and Big Spring. Eventually these cattle were sold to other, smaller ranches, and the Hat Ranch, once second in size only to the XIT in West Texas, had ceased to exist.