| Place Name | Irwin |
| Place Type | Borough |
| ZIP Code(s) | 15642 |
| County | Westmoreland County |
| Area Code(s) | 724,878 |
| Timezone | Eastern Daylight Time (EDT) |
| Population (2022) | 3,974 |
| Population Growth Rate (2010-19) | -1.79% |
| Majority Ethnicity | White 96.37% |
| Metro/Micro Stats Area | Pittsburgh, PA |
| US Congressional District(s) | Pennsylvania 18th |
| State House Districts | 56 |
| State Senate Districts | 39 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 96.37% |
| African American | 1.37% |
| Hispanic | 0% |
| Asian | 0% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 2.25% |