Where Does the Time Zone Change in Idaho?
The official Mountain–Pacific boundary is more precise than “north Idaho vs south Idaho.” Under 49 CFR §71.9, the line runs south along the Idaho–Montana border to the boundary between Idaho County and Lemhi County, then follows that county line southwest to the main channel of the Salmon River and follows the river west to the Idaho–Oregon boundary.
Boise and southern IdahoMountain Time. Boise uses MST in standard time and MDT during daylight saving time.
Coeur d’Alene and the PanhandlePacific Time. Northern Idaho cities such as Coeur d’Alene, Moscow and Sandpoint use PST/PDT.
Municipalities on the boundaryFederal regulations assign municipalities located on the Mountain–Pacific boundary line to Mountain Standard Time.
Why Is Idaho County in Two Time Zones?
Idaho County is unusually important to the state’s time-zone geography because the federal line reaches the Salmon River inside this part of Idaho. Areas north of the federal boundary use Pacific Time, while areas south of it use Mountain Time.
This is why broad labels such as “northern Idaho is Pacific” and “southern Idaho is Mountain” are useful for orientation but are not precise enough near the boundary. For travel, meetings and events close to the Salmon River, confirm the exact destination rather than assuming one statewide Idaho clock.
