The Collaborative International Dictionary of English v.0.48:

Presidio \Pre*si"di*o\, n. [Sp.]
   A place of defense; a fortress; a garrison; a fortress; a
   garrison or guardhouse.
   [1913 Webster]

WordNet (r) 3.0 (2006):

presidio
    n 1: a fortress established in the southwestern United States by
         the Spanish in order to protect their missions and other
         holdings; "Tucson was first settled as a walled presidio"

U.S. Gazetteer Counties (2000):

Presidio -- U.S. County in Texas
   Population (2000):    7304
   Housing Units (2000): 3299
   Land area (2000):     3855.505174 sq. miles (9985.712134 sq. km)
   Water area (2000):    0.749851 sq. miles (1.942105 sq. km)
   Total area (2000):    3856.255025 sq. miles (9987.654239 sq. km)
   Located within:       Texas (TX), FIPS 48
   Location:             29.986907 N, 104.235904 W
   Headwords:
    Presidio
    Presidio, TX
    Presidio County
    Presidio County, TX


U.S. Gazetteer Places (2000):

Presidio, TX -- U.S. city in Texas
   Population (2000):    4167
   Housing Units (2000): 1541
   Land area (2000):     2.572024 sq. miles (6.661512 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    2.572024 sq. miles (6.661512 sq. km)
   FIPS code:            59396
   Located within:       Texas (TX), FIPS 48
   Location:             29.561272 N, 104.366522 W
   ZIP Codes (1990):     79845
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Presidio, TX
    Presidio