1804 United States House of Representatives elections in Pennsylvania

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.

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 1st district (3 seats) consisted of Delaware and Philadelphia counties (including the City of Philadelphia)
• The 2nd district (3 seats) consisted of Bucks, Luzerne, Montgomery, Northampton, and Wayne Counties
• The 3rd district (3 seats) consisted of Berks, Chester, and Lancaster Counties
• The 4th district (2 seats) consisted of Cumberland, Dauphin, Huntingdon, and Mifflin Counties
• The 5th district consisted of Centre, Clearfield, Lycoming, McKean, Northumberland, Potter, and Tioga Counties
• The 6th district consisted of Adams and York Counties
• The 7th district consisted of Bedford and Franklin Counties
• The 8th district consisted of Armstrong, Cambria, Indiana, Jefferson, Somerset, and Westmoreland Counties
• The 9th district consisted of Fayette and Greene Counties
• The 10th district consisted of Washington County
• The 11th 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

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

Returns are incomplete for the 8th, 9th, and 10th districts

Special election to the 8th Congress

William Hoge (DR) of the 10th 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 4th district, John A. Hanna (DR) died on July 23, 1805, while in the 11th district, John Lucas (DR) resigned prior to the first meeting of the 9th Congress.

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

• Electoral data are from The Wilkes University Election Statistics Project