B
- Beaver County, Oklahoma: Beaver is named for its county seat of Beaver, Oklahoma and the Beaver River, which flows through the county.
- Benzie County, Michigan is an Americanization of the French name, Riviere Aux-Bec-Scies, for the local river.
- Blanco County, Texas: Blanco is named for the Blanco River. Blanco means white in the Spanish language.
- Boise County, Idaho: Boise is named after the Boise River. Boise is French for "timber".
- Bosque County, Texas: Bosque is named for the Bosque River.
- Brazoria County, Texas: Brazoria is named for the Brazos River.
- Brazos County, Texas: Brazos is named for the Brazos River.
- Buffalo County, Wisconsin: Buffalo is named for the Buffalo River.
Read more about this topic: List Of U.S. Counties Named After Rivers