The history of the United State Bank began in 1922 when Lorenzo H. Gnuse, Sr. founded the Durham State Bank. Mr. Gnuse was commissioned by the State of Missouri to assist in the liquidation of banks throughout Missouri that were failing due to the nationwide depression. Mr. Gnuse was sent to Durham to liquidate the Durham Savings Bank. The citizens of the community desired a new bank and Mr. Gnuse agreed to organize a new bank. 

Six years later the citizens of Lewistown, Missouri approached Mr. Gnuse to charter a new bank in Lewistown because the two banks in Lewistown had failed, again due to the depression. Mr. Gnuse with the help of his wife, Ida Gnuse, and brother, Solomon Gnuse, established the Lewistown State Bank in 1928. Both banks remained open during the depression. In 1936, the two banks were merged. 

In 1973, a branch was opened in Ewing, Missouri; and in 1991 a branch was opened in Edina, Missouri at which time the name of the bank was changed to United State Bank.

In March 2015, two branches were purchased and merged with the existing three branches under the United State Bank name. One in Palmyra, Missouri and another in Shelbina, Missouri.
In November 2020, a branch was purchased in Canton, Missouri and merged with the existing five branches under the United State Bank name.