Did You Know?
A City That Cannot Agree Where Its Own Mile Is
1. Denver's entire identity is one number: 5,280 feet. Exactly one mile.
2. Nobody can agree which step it is on.
The official marker sits on the steps of the Colorado State Capitol, and over the years it has been placed on three different steps.
- 1909 — surveyors identified the 15th step, which was engraved One Mile Above Sea Level. It held the title for sixty years.
- 1969 — students from Colorado State University remeasured and put the mile on the 18th step. A bronze marker was installed.
- 2003 — measured again. This time the answer was the 13th step, where the marker sits today.
Three steps, a century of changing survey technique, three different answers to a question that has one correct value.
3. Modern GPS suggests all three may be slightly wrong.
In 2026 a new survey, based on NOAA's updated national height data, put the mile on the 17th step — four steps above the current marker; a new official marker is due in 2027. Across the metro area the ground ranges from roughly 5,130 to 5,690 feet, and Denver International Airport sits higher than downtown at about 5,430 feet, making it the highest major airport in the United States.
4. The city marks the line anyway, repeatedly.
Coors Field has a row of 865 purple seats running around the upper deck, set at exactly one mile above sea level. City Park has the Mile High Loop, a 3.1-mile trail that follows the 5,280-foot contour — a 5K that never changes altitude.
The altitude is not decorative. Water boils at about 203°F here instead of 212°F, which changes cooking times and forces recipe adjustments. Denver is one of the sunnier big US cities, because the thin dry air holds little moisture to form cloud — though the famous 300 days of sunshine a year began as a railroad publicist's slogan in the 1870s.
The clock: and here is the part that makes Denver unusual on this site.
The 105th meridian west — the longitudinal reference line for the entire Mountain Time Zone — passes directly through Denver Union Station.
Almost every city in this project is displaced from its own zone meridian by minutes: Reykjavík's clock runs roughly ninety minutes ahead of its sun, İzmir's seventy-one ahead, and Boston's sixteen behind. Denver sits exactly on that meridian, so on standard time its clock and its sun reach midday at effectively the same instant. (In summer, daylight saving puts the clock an hour ahead.)
So: a city that has measured its own height four times since 1909 and is still moving the mark — and whose clock is, as far as this site can determine, the most accurate of all the cities on it.
Sources
- Atlas Obscura, *Mile-High Steps at the Colorado State Capitol* (15th step and "One Mile Above Sea Level" inscription in 1909, until 1969; 18th step and bronze marker measured by Colorado State University students in 1969; 13th step in 2003)
- Visit Denver (metropolitan elevation ranges from 5,130-5,690 feet; 865 purple seats at Coors Field; 3.1-mile Mile High Loop at City Park)
- Denverite, *Fourth time's the charm for Denver's mile-high marker* (July 2026: 17th step; official marker delayed to 2027); NOAA National Geodetic Survey, *Moving Mountains* (new height datum)
- StudyGuides.com (water boils at ~203°F at 5,280 feet, 212°F at sea level)
- Altitude Control (Denver International Airport ~5,430 feet)
- elevation-check.com (alcohol acts harder at altitude); Westword (the 300-days-of-sunshine claim began as an 1870s railroad publicist's slogan)
- **Wikipedia, *Denver*: The 105th meridian west — the longitudinal reference of the Mountain Time Zone — passes directly through Denver Union Station**