Rostraver Township is a township in Westmoreland County, Pennsylvania, United States. The population was 11,634 at the 2000 census.
Rostraver Township is in the southwestern corner of Westmoreland County and is the location of the Household No. 1 Site, which was once occupied by a Monongahela village. It is listed on the National Register of Historic Places.
The name of the township has been traced back to Rostrevor, a seaside community in County Down, Ireland. It is known that some of the early settlers, such as the McClains, came from County Down so it is surmised that they probably named their new community out of affection for the native village and spelled it phonetically as Rostraver. Unfortunately, they neglected to leave to posterity any record of having done so.
According to the United States Census Bureau, the township has a total area of 32.9 square miles (85.2 km²), of which, 32.2 square miles (83.4 km²) of it is land and 0.7 square miles (1.8 km²) of it (2.13%) is water.