What states are in the Mountain Standard Time zone?
Understanding Mountain Standard Time (MST)
Navigating time zones in the United States can be tricky because state borders do not always align perfectly with the longitudinal lines that define time. Mountain Standard Time (MST) is one of the four primary time zones in the contiguous United States, sitting between Central Time and Pacific Time.
Defining the Zone
Mountain Standard Time is defined as Coordinated Universal Time minus seven hours (UTC-7). However, it is important to distinguish between Standard Time and Daylight Saving Time (DST). During the summer months, most of these regions shift to Mountain Daylight Time (MDT), which is UTC-6. Arizona is a notable exception, as it generally does not observe Daylight Saving Time.
States Within the Mountain Time Zone
Because time zone boundaries are often determined by political and economic convenience rather than strict geography, some states are split between two time zones. Here is a breakdown of the states that fall entirely or partially within the Mountain Time Zone:
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Entirely in Mountain Time: Colorado, Montana, New Mexico, Utah, and Wyoming.
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Partially in Mountain Time: Idaho (the southern portion), Oregon (a small eastern section), Nevada (most of the state), Arizona (the entire state, though it stays on MST year-round), North Dakota (the western half), South Dakota (the western half), Nebraska (the western portion), Kansas (the far western counties), and Texas (the far western tip near El Paso).
Quick Reference Table
| State Status | Examples |
|---|---|
| Entirely Mountain | Colorado, Montana, New Mexico, Utah, Wyoming |
| Split States | Idaho, Nevada, North Dakota, South Dakota, Nebraska, Kansas, Texas |
Real-World Examples
If you are traveling across the country, you might notice the shift in time as you cross the border from Eastern Colorado (Mountain Time) into Western Kansas (which is split). If you are in Denver, you are firmly in the heart of the Mountain Time Zone. If you are in El Paso, Texas, you are in the only part of Texas that observes Mountain Time, while the rest of the state follows Central Time.
Common Pitfalls
One of the most common mistakes travelers make involves Arizona. Because Arizona does not observe Daylight Saving Time, it remains on Mountain Standard Time all year. This means that during the summer, Arizona is actually on the same time as the Pacific Daylight Time zone, even though it is geographically located in the Mountain zone. Always check local time if you are traveling to the Southwest during the warmer months!