McClain County National Bank was chartered on March 8, 1922, right here on Main Street in Purcell. Officers at the time consisted of John H. Perry as President, E.L. Sheets as Vice President, and John H. Wells as Cashier. Six months later, at the close of business on September 15, the Bank had total assets of $298,212.95. In 1927, the Bank purchased Chickasaw National Bank of Purcell.
The Sherman family's involvement with the Bank began in 1935 when Earl Sherman began working here. The next year, he convinced his brother Neil, who was teaching in Lexington, to come work with him. That same year, 1936, the Bank purchased the First State Bank of Wayne. In 1941, the Bank also purchased the Byars State Bank.
By 1955, control of the bank was vested in two families - the Wells and the Shermans. But in 1980, the Sherman Family acquired complete control of McClain County National Bank.
In 1990, the FDIC closed the First National Bank of Purcell and First State Bank of Lexington. The Bank purchased both from the FDIC.
A new millennium brought a new name, with McClain County National Bank changing its name to McClain Bank in 2001 in preparation of increased presence in Norman and Cleveland County. On October 22, 2002, the McClain Bank Norman Branch held its ribbon cutting at 2900 W Lindsey. The facility is located on five acres. On April 4, 2007, the McClain Bank Noble Branch held its ribbon cutting at 213 N Main Street.