The Collaborative International Dictionary of English v.0.48:

Midwest \Midwest\ n.
   The north central region of the U. S.

   Syn: Middle West.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Midwest
    n 1: the north central region of the United States (sometimes
         called the heartland or the breadbasket of America) [syn:
         Midwest, middle west, midwestern United States]

U.S. Gazetteer Places (2000):

Midwest, WY -- U.S. town in Wyoming
   Population (2000):    408
   Housing Units (2000): 228
   Land area (2000):     0.442519 sq. miles (1.146118 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.442519 sq. miles (1.146118 sq. km)
   FIPS code:            52445
   Located within:       Wyoming (WY), FIPS 56
   Location:             43.408203 N, 106.278114 W
   ZIP Codes (1990):     82643
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Midwest, WY
    Midwest