1804 United States House of Representatives elections in Pennsylvania

Elections to the United States House of Representatives were held in Pennsylvania on October 9, 1804, for the 9th Congress.

Background
In the previous election, a delegation of all Democratic-Republicans had been elected to Congress. At this time, a moderate wing of the Democratic-Republican party, known as the Constitutional Republicans or tertium quids ("quids" for short) had broken off from the majority and ran candidates in several districts. The Quids were generally allied with the Federalists.

Congressional districts
Pennsylvania was divided into 11 districts, of which four were plural districts with 11 Representatives between them. Several new counties were created between the 1802 elections and the 1804 elections. The districts were:
 * The PA's 1st congressional district (3 seats) consisted of Delaware and Philadelphia counties (including the City of Philadelphia)
 * The PA's 2nd congressional district (3 seats) consisted of Bucks, Luzerne, Montgomery, Northampton, and Wayne Counties
 * The PA's 3rd congressional district (3 seats) consisted of Berks, Chester, and Lancaster Counties
 * The PA's 4th congressional district (2 seats) consisted of Cumberland, Dauphin, Huntingdon, and Mifflin Counties
 * The PA's 5th congressional district consisted of Centre, Clearfield, Lycoming, McKean, Northumberland, Potter, and Tioga Counties
 * The PA's 6th congressional district consisted of Adams and York Counties
 * The PA's 7th congressional district consisted of Bedford and Franklin Counties
 * The PA's 8th congressional district consisted of Armstrong, Cambria, Indiana, Jefferson, Somerset, and Westmoreland Counties
 * The PA's 9th congressional district consisted of Fayette and Greene Counties
 * The PA's 10th congressional district consisted of Washington County
 * The PA's 11th congressional district consisted of Allegheny, Beaver, Butler, Crawford, Erie, Mercer, Venango, and Warren Counties

The borders between the 4th, 5th, and 8th districts were altered slightly in the erection of new counties from parts of several counties

Note: Many of these counties covered much larger areas than they do today, having since been divided into smaller counties

Election results
Fifteen incumbents ran for re-election, of whom 14 won. The incumbents Isaac Van Horne (DR) of the PA's 2nd congressional district, Joseph Hiester (DR) of the PA's 3rd congressional district and William Hoge (DR) of the PA's 10th congressional district did not run for re-election. One seat changed from Democratic-Republican to Federalist.

Returns are incomplete for the PA's 8th congressional district, PA's 9th congressional district, and PA's 10th congressional district districts

Special election to the 8th Congress
William Hoge (DR) of the PA's 10th congressional district resigned October 15, 1804. A special election was held November 2, 1804 to fill his seat for the remainder of the 8th Congress

John Hoge was William's brother.

Special elections to the 9th Congress
Two special elections were held on October 8, 1805. In the PA's 4th congressional district, John A. Hanna (DR) died on July 23, 1805, while in the PA's 11th congressional district, John Lucas (DR) resigned prior to the first meeting of the 9th Congress.

Michael Leib (DR) of the PA's 1st congressional district resigned February 14, 1806. A special election was held November 27, 1806