| Senate Name | County | Dist. # | Party | Session # | Dates | Notes |
|---|
|
|
| Imbrie, deLorma | 25 | Beaver, Butler | Rep | 84 | 1860 |
| Imbrie, deLorma | 25 | Beaver, Butler | Rep | 85 | 1861 |
| Imbrie, deLorma | 25 | Beaver, Butler | Rep | 86 | 1862 |
| Ingram, Harlan G. | 2 | Philadelphia (old county) | Dem | 80 | 1856 |
| Ingram, Harlan G. | 2 | Philadelphia (old county) | Dem | 81 | 1857 |
| Ingram, Harlan G. | 1 | Philadelphia | Dem | 82 | 1858 |
| Irish, Elias H. | 24 | Allegheny | Rep | 84 | 1860 |
| Irish, Elias H. | 24 | Allegheny | Rep | 85 | 1861 |
| Irish, Elias H. | 24 | Allegheny | Rep | 86 | 1862 |
| Irish, Nathaniel | | Allegheny, Beaver, Butler | Rep | 33 | 1808-09 |
| Irvin, Alexander | 13 | Lycoming, Centre, Clearfield, McKean, Potter | Dem | 60 | 1835-36 |
| Irvin, Alexander | 14 | Lycoming, Centre, Clearfield, McKean, Potter | Dem | 61 | 1836-37 |
| Irvin, Alexander | 23 | Indiana, Armstrong, Cambria, Clearfield | Dem | 62 | 1837-38 |
| Irvin, Edward A. | 34 | Clinton, Clearfield, Centre | Rep | 116 | 1905-06 |
| Israel, Israel | | Philadelphia City, Philadelphia, Delaware | Rep | 22 | 1797-98 |
| Ives, Timothy | 28 | Warren, Jefferson, Clarion, McKean, Potter | Dem | 73 | 1849 |
| Ives, Timothy | 28 | Warren, Jefferson, Clarion, McKean, Potter | Dem | 74 | 1850 |
| Ives, Timothy | 18 | Tioga, Potter, McKean, Elk, Clearfield, Jefferson | Dem | 75 | 1851 |