Founded in 1904 as a private bank by John Walter Knorpp, a member of an established banking family of Missouri, New Mexico, and Texas, and Eugene Sherwood Blasdel, a developer of the region's oil and grain business, State National Bank changed when Blasdel sold his interest to Knorpp in 1905. It received a state charter in 1908 and surrendered it in 1926 for a national charter. Supported by the patronage of diligent, thrifty early settlers, the bank advanced with leadership that included members of the pioneer Britten, Fields, Fraser, Harrell, Johnson, Krizan, Slay, and Steele families on its board of directors. I. C. Unsell served as cashier from 1908 to 1932, and Cecil Culver, who came to the bank in 1929 as assistant cashier, purchased the controlling interest from Knorpp and became president in 1951. Adapting to regional crises, the bank weathered the panic of 1907, the Dust Bowl adversities of the 1930s, two World Wars, and other national and international experiences, and it continues to support the cattle, grain, oil, beef feedlot, and other agribusiness interests and the cultural facilities of Groom and the surrounding area.