 However, the overall richest area is the Delaware Valley, which is composed of suburban Philadelphia, and is located in a wealth corridor that runs from the suburbs of Washington, DC all the way into southern New Hampshire.In contrast to the Delaware Valley, the wealthy Pittsburgh neighborhoods are more condensed into small locations, while the wealthy Philadelphia communities spread out over four counties (Bucks, Chester, Delaware, and Montgomery) and within the city’s borders.One notable wealthy area in the Philadelphia area is the Pennsylvania Main Line, which includes Lower Merion, Radnor, Tredyffrin, Easttown, and Willistown townships.