Boldface (with superscript C) numbers indicate the majority Party in each house. Red (with superscript P) numbers (boldface or not) indicate the Party of the President in any event.
| President | Party | Congress | United States Senate | House of Representatives | |||||
|---|---|---|---|---|---|---|---|---|---|
| Republican | Federalist | other | vacancies | Republican | Federalist | other | |||
| Monroe | Republican | 15th 1817-1819 | 29CP | 11 | |||||
15th CONGRESS- in General SENATE: 29 Republicans, 11 Federalists MISSISSIPPI was admitted as the 20th State of the Union on 10 December 1817; As Mississippi's 2 Senators were elected by the Legislature of the State and Mississippi's 1 Congressman was elected by the People within that State before the end of the odd-numbered year in which the 15th Congress took office [this being 1817], Mississippi's Senators and Congressman are, therefore, counted among the members of the Senate and the House of Representatives elected to that Congress. ILLINOIS was admitted as the 21st State of the Union on 3 December 1818: as this was well after the end of the odd-numbered year in which the 15th Congress took office [this being 1817], Illinois' 2 Senators are NOT counted among those elected to the Senate of the 15th Congress; neither is Illinois' 1 Congressman counted among those elected to the House of Representatives in that Congress. | |||||||||
Modified .