Pennsylvania's 18th congressional district includes parts of Washington County, Allegheny and Westmoreland Counties. Republican Tim Murphy has represented the district since 2003. The district is concentrated in the southern suburbs of Pittsburgh. It is predominantly white and affluent, although it contains a diverse range of suburbs. It is drawn in such a way that in some locations, neighborhoods and even streets are split between the 18th and the neighboring 12th and 14th districts. In parts of the eastern portion of the district, one side of the street is in the 12th while the other side is in the 18th. In the west, one side of the street is in the 14th while the other side is in the 18th.