| | Beaverhead County | MT | 30001 | | | | | nonmetro county (rural) | federal/state
government-dependent | https://maps.google.com/?q=BeaverheadCounty+MT |
| | Big Horn County | MT | 30003 | | | | | nonmetro county (rural) | mining-dependent | https://maps.google.com/?q=BigHornCounty+MT |
| | Blaine County | MT | 30005 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=BlaineCounty+MT |
| | Broadwater County | MT | 30007 | | Helena, MT 25740 | | Outlying | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=BroadwaterCounty+MT |
| | Carbon County | MT | 30009 | | Billings, MT 13740 | | Outlying | metro county (urban) | recreation | https://maps.google.com/?q=CarbonCounty+MT |
| | Carter County | MT | 30011 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=CarterCounty+MT |
| | Cascade County | MT | 30013 | | Great Falls, MT 24500 | | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=CascadeCounty+MT |
| | Chouteau County | MT | 30015 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=ChouteauCounty+MT |
| | Custer County | MT | 30017 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=CusterCounty+MT |
| | Daniels County | MT | 30019 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=DanielsCounty+MT |