A special election was held in Massachusetts's 8th congressional district on October 16, 1820 and November 24, 1820 to fill a vacancy caused by the resignation of Zabdiel Sampson (DR) on July 26, 1820.
Election results
Although a majority was achieved on the first ballot, a second election was ordered because elections had not been held in the town of Hanson
Hobart took his seat on December 18, 1820
References
Massachusetts's 8th congressional district special election, 1820 Wikipedia(Text) CC BY-SA