On July 25, 1822, William Hendricks (DR) of Indiana's at-large district resigned to run for Governor of Indiana. Hendricks had represented the state since it was first admitted to the Union.
Election results
Jennings had previously served as delegate for Indiana Territory in the 11th through 14th Congresses. Jennings took his seat December 2
References
Indiana's at-large congressional district special election, 1822 Wikipedia(Text) CC BY-SA