During the Civil War John Bunyan Slaughter first put the U Lazy S brand on some calves given him by his father, George Webb Slaughter. The brand was reportedly chosen because of the `U. S.' in the United States; he changed it by reclining the `S', in imitation of the "Lazy S" brand of his oldest brother, C. C. Slaughter. Then he left the calves to grow up and multiply in Palo Pinto County, where the brand was first registered in the fall of 1866. John Slaughter started working at the age of seventeen as a trail hand for his father and brother. In 1877 he formed a partnership with his younger brother, William B. Slaughter, and for three years they bought cattle in Texas and drove them to Kansas, where they sold them at a profit. In 1880 they located a ranch on Scallowag (Home) Creek in Crosby County. Four years later, when the Espuela Land and Cattle Company (see SPUR RANCH) acquired title to the land they were using, the Slaughters trailed their cattle to Socorro County, New Mexico. In 1886 they sold their cattle and range rights to an English syndicate for $125,000. After the partnership was dissolved, John Slaughter located a ranch on the Green River in Utah, thirty miles east of Salt Lake City. Ranching there was not to his liking, however, and in 1888 he sold his cattle and returned to New Mexico, where he located near the Texas line. In 1890 he acquired 160 sections of land in Glasscock County, where for eight years his herd averaged 6,000 head. In 1898 he disposed of his Glasscock County holdings and moved his cattle to Borden and Garza counties.
In 1901 Slaughter purchased the Square and Compass Ranch and 5,000 cattle from the Nave-McCord Cattle Company in Garza and Lynn counties. In the transaction he acquired title to 99,188 acres at $1.60 an acre, and the U Lazy S finally had a permanent home. Slaughter built a spacious ranchhouse in 1902 and over the next few years purchased other tracts that brought the total to 126,227 acres. In 1906 he sold 45,749 acres for three dollars an acre to Charles W. Post, who in turn colonized the town of Post. Between 1905 and 1910 some 15,000 to 18,000 cattle bore the U Lazy S brand. In addition, the ranch raised hogs and a herd of buffalo, from which Slaughter successfully bred the Vernier, a buffalo-Brahman cross, although the breed had no economic value. Slaughter continually improved his operations with fences, water tanks, windmills, corrals, and dipping vats. He sold all his steers annually and kept his heifers in the breeding herd. In 1925 the ranch was made a state game preserve, to which Slaughter had five deer shipped from South Texas; from these grew the deer herd that now populates the area.
After Slaughter's death in 1928, his son John, Jr., (Jay) succeeded him as owner-manager of the U Lazy S. Under his direction several acres were broken up into farms, and a brick school was built for the Graham Community, which grew from these farms. He also experimented with the preservation of butchered beef and pork in the days before refrigeration and during the 1930s carried out the first mesquite-control program utilizing mechanical root plowing in West Texas. By 1936 8,000 Hereford cattle grazed 100,000 acres of U Lazy S land. The ranchhouse, enlarged and remodeled from time to time, became a West Texas landmark. As the years passed the Slaughters filled it with elegant furniture and art. On January 13, 1937, the house burned, carrying with it art treasures and documentary records of John B. Slaughter's land and colorful career on the Southwest frontier. Jay Slaughter died childless in 1940. His nephew and niece, John F. Lott and Mary Belle Lott Macy, formed a partnership and assumed joint management of the ranch. Lott, a dedicated conservationist, advocated farmland terracing, erosion control, and more efficient use of land. In 1949 he first used an airplane, a Piper Super Cub, for running cattle, maintaining the ranch water supply, spraying herbicides for mesquite control, and experimental cloud seeding. He also experimented with artificial insemination of beef cattle. By 1948 the U Lazy S comprised 78,578 acres, of which 7,000 acres was in farms. The ranch branded 3,000 calves annually by that time and continued to hold traditional roundups in the open with a chuck wagon. In January 1965 Lott and his sister terminated their joint ownership and divided the ranch into two parts. Subsequently the Macy Ranch used a Running M brand and was managed by Bob Macy. After Lott retired from active ranching, the U Lazy S was managed by his son Jack. In 1970 the heirs of John B. Slaughter gave the old U Lazy S carriage house, which dates from the turn of the twentieth century, to the Ranching Heritage Center in Lubbock.