WordNet (r) 3.0 (2006):

Northumberland
    n 1: the northernmost county of England; has many Roman remains
         (including Hadrian's Wall)

U.S. Gazetteer Counties (2000):

Northumberland -- U.S. County in Pennsylvania
   Population (2000):    94556
   Housing Units (2000): 43164
   Land area (2000):     459.910657 sq. miles (1191.163083 sq. km)
   Water area (2000):    17.468738 sq. miles (45.243823 sq. km)
   Total area (2000):    477.379395 sq. miles (1236.406906 sq. km)
   Located within:       Pennsylvania (PA), FIPS 42
   Location:             40.863236 N, 76.687307 W
   Headwords:
    Northumberland
    Northumberland, PA
    Northumberland County
    Northumberland County, PA


U.S. Gazetteer Counties (2000):

Northumberland -- U.S. County in Virginia
   Population (2000):    12259
   Housing Units (2000): 8057
   Land area (2000):     192.302023 sq. miles (498.059931 sq. km)
   Water area (2000):    93.363253 sq. miles (241.809705 sq. km)
   Total area (2000):    285.665276 sq. miles (739.869636 sq. km)
   Located within:       Virginia (VA), FIPS 51
   Location:             37.867360 N, 76.372080 W
   Headwords:
    Northumberland
    Northumberland, VA
    Northumberland County
    Northumberland County, VA


U.S. Gazetteer Places (2000):

Northumberland, PA -- U.S. borough in Pennsylvania
   Population (2000):    3714
   Housing Units (2000): 1772
   Land area (2000):     1.568288 sq. miles (4.061848 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    1.568288 sq. miles (4.061848 sq. km)
   FIPS code:            55456
   Located within:       Pennsylvania (PA), FIPS 42
   Location:             40.893935 N, 76.795975 W
   ZIP Codes (1990):     17857
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Northumberland, PA
    Northumberland