In 1884, Stephen Tompkins established a banking firm connected with Tompkin's mercantile business. It was known as "S. Tompkins and Son" and was located on the northeast corner of Main and Clinton Street in the old "Tompkins Brick" building he had constructed in 1856. The building stood were the Avon Fire Station is now located. 

In 1892 the Tompkins firm purchased and moved into the two story building on the southeast corner of Main and Washington Street. It was known as the "Opera House Block", and was built in 1879 by O.J. Beam. 

The building served as quarters for the bank in the north rooms and a dry goods store on the south side. Later, a one story grocery store was added and entrance could be gained from the businesses in the bank building through an interior archway. 

Two other businesses, a restaurant and a barber shop were housed in the basement of the bank building and could be entered from inside or by approaching exterior basement stairs at the front of the bank building. With the Opera House on the second floor and several businesses all easily accessible from within, the establishments created an early day mini-mall. 

In 1899 at the death of his father, Stephen, Albert Tompkins sold his interest in the store and became president of the bank. It was then reorganized into a partnership known as A.B. Tompkins and Company. Partners included his brother, Frank and his son-in-law, Harry S. Clayberg. 

The status of the bank was changed from a private bank to a state bank rating in 1913 and became known as Tompkins State Bank with officers and a board of directors. 

In March 1933 all banks in the United States were closed by an order of the government. Tompkins heirs owned a controlling interest in the bank at the time of the closing. A committee of citizens realizing that the town needed a bank met with the heirs and devised a workable plan. They felt the bank would be more successful if the stock was more widely distributed in the community. 

The committee sold sufficient shares at $50 each to raise the required cash to re-open for business September 25, 1933 and succeeded in paying off all of the $163,000 in waived deposits.

In April of 1991, Tompkins State Bank expanded and opened an office in Abingdon. In 2005, the Avon location was remodeled and the bank added a second building for data processing and a more convenient drive thru location. Today, Tompkins State Bank is still going strong with two additional offices in Knox County. In February of 2006, a new office was built in Knoxville located at the junction of County Highway 10 and US Route 150. In December of 2008, Tompkins State Bank acquired Community Bank of Galesburg located on North Henderson Street in Galesburg.