List of members of the United States House of Representatives in the 21st Congress by seniority

This is a complete list of members of the United States House of Representatives during the 21st United States Congress listed by seniority.

As an historical article, the districts and party affiliations listed reflect those during the 21st Congress (March 4, 1829 – March 3, 1831). Current seats and party affiliations on the List of current members of the United States House of Representatives by seniority will be different for certain members.

Seniority depends on the date on which members were sworn into office. Since many members are sworn in on the same day, subsequent ranking is based on previous congressional service of the individual and then by alphabetical order by the last name of the congressman.

Committee chairmanship in the House is often associated with seniority. However, party leadership is typically not associated with seniority.

Note: The "*" indicates that the representative/delegate may have served one or more non-consecutive terms while in the House of Representatives of the United States Congress.