A parish in northwest Louisiana covering 852 square miles and containing eleven municipalities:
Belcher,
Blanchard,
Gilliam,
Greenwood,
Hosston,
Ida,
Mooringsport,
Oil City,
Rodessa,
Shreveport, and
Vivian.
The population of Caddo Parish, Louisiana, is 247,000 according to the last Census, but currently there's more than that in Shreveport alone.
The parish is bordered by Arkansas to the north, Texas to the west, DeSoto Parish, Louisiana, to the south, the Red River and Bossier Parish, Louisiana, to the east. A small southeastern section of the parish borders Red River Parish, Louisiana.
There's more at http://www.caddo.org.