Bill, the average household income for Philadelphia was $40,227 according to the 2000 US Census ( http://factfinder.census.gov/servlet/QTTable?ds_name=D&geo_id=05000US42101&qr_name=ACS_C2SS_EST_G00_QT03&_lang=en ).
Here is the US household income breakdown per state (for year 2000), for the curious:
United States 42,148
Maryland 51,695
Alaska 50,746
New Jersey 51,032
Connecticut 50,360
Minnesota 50,865
Colorado 48,506
New Hampshire 48,928
Virginia 50,069
Delaware 50,154
Illinois 46,435
Utah 45,230
Washington 42,024
Michigan 46,181
Massachusetts 46,947
Hawaii 48,026
Wisconsin 45,349
California 46,802
Missouri 47,462
Rhode Island 42,973
Nevada 44,755
Ohio 43,894
Oregon 42,440
Iowa 42,993
Georgia 42,887
Pennsylvania 43,742
Indiana 39,717
Vermont 38,150
New York 41,605
Maine 41,597
Arizona 41,456
Texas 39,842
Nebraska 38,574
North Carolina 38,829
Kansas 37,705
Wyoming 39,026
District of Columbia 38,752
Idaho 37,462
Florida 37,998
Kentucky 37,186
South Carolina 37,119
Alabama 33,105
South Dakota 36,172
Tennessee 33,885
New Mexico 35,254
Oklahoma 32,445
North Dakota 35,349
Montana 32,045
Louisiana 30,219
Mississippi 31,528
Arkansas 30,293
West Virginia 29,052