Patrick H. and John Landergin, cattlemen, were the sons of Irish immigrants who immigrated to the United States as a result of the potato famine in the 1840s. They established a dairy farm near Oxford, New York, where Patrick was born on March 3, 1854, and John on March 26, 1856. The boys attended school and worked on their father's farm. Later, Pat taught school while John completed his education. In 1870 the brothers went west to Indian Territory, where they invested their savings in a herd of longhorn cattle that they grazed along the Red River. The next year the Landergins drove 1,040 cattle over the Chisholm Trail and settled near Coffeyville, Kansas. In 1879 they purchased three small ranches totaling 2,600 acres near Eureka, in Greenwood County, where they made a fortune by fattening cattle and shipping them to markets in England. In 1886 Pat Landergin returned briefly to Oxford, where he married Mary Louisa Corbin on November 28. The newlyweds then joined John in Eureka, where their two daughters were later born. As a result of their financial success, the Landergin brothers became directors in the Eureka Bank and were involved in the Kansas National Livestock Association, of which Pat served as a director. In addition, Pat was on the board of regents of Fairmount College (now Wichita State University), and was a regent of Eureka College. In 1903 he was elected to the Kansas House of Representatives on the Democratic ticket.
The disastrous decline in the cattle market at the turn of the century prompted the Landergins to seek out a new range in which to recoup their losses. The brothers had relied for some time on cattle from the Texas Panhandle to supply their ranches, so they sought to rebuild their business there. In 1904 they leased, with a five-year option to buy, the western portion of the LS Ranch in Oldham County. When Frederick H. Kreismann put the LS up for sale in January 1905, he tried to persuade the Landergins to surrender their contract to the buyer, Swift and Company of Chicago. However, the brothers refused to release their option, and despite a lawsuit and other problems, they were able to clear their debts in three years. In April 1907 they purchased the 92,000-acre ranch for $203,448 and established their home at the old Alamosa Creek headquarters. After buying some steers from Charles Ewell, an Arizona rancher, they adopted his UL (connected) brand as their own. In 1908 Pat Landergin became director of the Vega Town Company, and both he and John were instrumental in founding the town on the southern boundary of their range. They established the First State Bank at Vega, of which Pat was president for the remainder of his life.
In the spring of 1911 the Landergins expanded their operations by taking a five-year lease on about 100,000 acres of XIT Ranch land in Oldham and Deaf Smith counties, which they subsequently bought. They acquired an interest in the Bravo Ranch in Hartley County, which they sold to John M. Shelton in 1915, and later purchased an interest in the Double Circle Ranch near Clifton, Arizona. In 1920 they bought land in Lipscomb County for use as a bull ranch and increased their herds with range cows from the Bell Ranch near Logan, New Mexico.
The Landergins resided at the Alamosa headquarters until 1912, when they moved to Amarillo and built a mansion at 1600 Polk Street. In Amarillo they became officers in several cattlemen's associations on the local, regional, and national level. Pat also was president of the Tri-State Fair in 1916, and a director of the American State Bank. In 1921, faced with another recession in the cattle market and mounting debts from the XIT land purchases, the Landergins decided to incorporate their business activities as the Landergin Brothers Company. At that time the brothers had stock in the Amarillo Oil Company and with Eugene S. Blasdel were involved in locating the Panhandle's first successful oil well. Nevertheless, in seeking oil and gas deposits on their own land, the Landergins were far less fortunate and in the end profited little from the oil boom. Attempts at sheep ranching likewise ended in failure. Consequently the company throughout the 1920s sold much of its vast range land to smaller farmers and ranchers.
John Landergin, who had never married, died on June 23, 1923. His loss as the stabilizing force in the family business was keenly felt, and the company was subsequently plunged deeper into debt. Patrick Landergin died on March 4, 1929, and was buried in the Llano Cemetery, Amarillo. Frank Donegan, the brothers' nephew and executor, continued to manage the company's affairs. Although he continued to invest in oil and gas leases, losses mounted, especially after the discovery of the East Texas oilfield resulted in a drop in oil prices in 1930. What was more, the severe drought of the depression era curtailed the corporation's agricultural output. After Donegan's death in 1942, Grady C. Nobles began the process of selling the remaining cattle and ranchlands and liquidating the company assets, which he accomplished in April 1950.