| | Ada County | ID | 16001 | | Boise City, ID 14260 | Boise City-Mountain
Home-Ontario, ID-OR 147 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=AdaCounty+ID |
| | Adams County | ID | 16003 | | | | | nonmetro county (rural) | federal/state
government-dependent | https://maps.google.com/?q=AdamsCounty+ID |
| | Bannock County | ID | 16005 | | Pocatello, ID 38540 | | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=BannockCounty+ID |
| | Bear Lake County | ID | 16007 | | | | | nonmetro county (rural) | recreation | https://maps.google.com/?q=BearLakeCounty+ID |
| | Benewah County | ID | 16009 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=BenewahCounty+ID |
| | Bingham County | ID | 16011 | | Blackfoot, ID 13940 | Idaho
Falls-Rexburg-Blackfoot,
ID 292 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=BinghamCounty+ID |
| | Blaine County | ID | 16013 | | Hailey, ID 25200 | | Central | nonmetro county (rural) | recreation | https://maps.google.com/?q=BlaineCounty+ID |
| | Boise County | ID | 16015 | | Boise City, ID 14260 | Boise City-Mountain
Home-Ontario, ID-OR 147 | Outlying | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=BoiseCounty+ID |
| | Bonner County | ID | 16017 | | Sandpoint, ID 41760 | | Central | nonmetro county (rural) | recreation | https://maps.google.com/?q=BonnerCounty+ID |
| | Bonneville County | ID | 16019 | | Idaho Falls, ID 26820 | Idaho
Falls-Rexburg-Blackfoot,
ID 292 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=BonnevilleCounty+ID |