Founded in 1904 as a private bank by John Walter Knorpp (1867-1952), member of an established banking family of Missouri, New Mexico, and Texas, and Eugene Sherwood Blasdel (1878-1930), oil and grain business developer of this region. In 1905 Blasdel sold his interest to Knorpp. A state charter was obtained in 1908, but surrendered in 1926 for national charter.
Patronage from diligent, thrifty early settlers advanced the career of this bank. On its Board of Directors have been members of the pioneer Britten, Fields, Fraser, Harrell, Johnson, Krizan, Slay, and Steele families. I. C. Unsell was cashier from 1908 to 1932.
Cecil Culver (born 1903), who came to the bank in 1929 as assistant cashier, purchased the controlling interest from Knorpp and became president in 1951.
Adjusting to the crises in the region, State National Bank weathered the panic of 1907, the adversities of the 1930s Dust Bowl, two World Wars, and other national and international experiences. It continues to bolster the cattle, grain, oil, beef feedlot, and other agribusiness interests, and the cultural facilities of Groom and surrounding area.