Mile High marker in Denver

Denverite.com does not believe I am human.  As President Nixon once said, "I am not a bot."

Denverite sounds like a mineral.

The story was pretty good, at least compared to some of the stories about the four corner monument.

Here's an article on it: https://www.denver7.com/news/colorado-150/history-repeats-itself-mile-high-mark-at-the-colorado-state-capitol-moves-for-a-fourth-time

It's a strange article to me since it makes no mention at all about the different vertical datums, and what's a centimeter inch? Sounds like an allergy.

@mountainhermit 

I believe "inch" was supposed to be "each".

Posted by: @kscott

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Interesting story from Denver.

https://denverite.com/2026/06/16/denver-mile-high-marker-moving/

"More right" is what the article calls it.

Is all this stuff is done by people that don't have a payroll to make or partners to answer to?

Don't move the marker, and you aren't smarter than the people that came before, no matter how many times you change the answer.

(And yes, I am a grumpy old man.)

The new elevations will be based on gravity measurements. The original gravity measurements were taken across the US every 300' or so. Seems it was a very accurate survey by those survey crews. New elevations locally will shift about 2' lower than NAVD88 which shifted 2.4' higher than NGVD 29. There needs to be a shout-out to our betters, the men that surveyed before us. 

Gravity is mysterious, they still don't have a good handle on it. It can be measured but the force is not understood so the idea that the new values are the finished product is iffy at best.

Posted by: @mightymoe

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There needs to be a shout-out to our betters, the men that surveyed before us. 

There is ±3.5 feet of difference between '29 and '88 in the PDX area. Early indications are that the difference between '29 and '2022 will be under a tenth.  

In my neck of the woods 88 is about 0.42' higher than 29.

Had a surveyor call me once about a site plan where I had provided all of the "PRE" data they needed.  He was in a tizzy.  He was telling me that all of my elevation information was off by some number close to three feet.  I assured him that he had something terribly wrong as no changes had been made since I had been onsite as I drove past the site on a regular basis.  I provided him with Highway plans for both the adjacent highway and the crossing highway about 1000 feet north of the site plus the overpass data.  The manhole rims he had shot were in agreement with the highway data and a network of benchmarks across the city.  He told me I didn't know anything.

The strange thing is that I never received a callback from him apologizing for being a ignorant jackass.

Out here on the east coast.

NAVD88 (Computed using GEOID18) OPUS 4hr data set 330.173 (± 0.066) m

DESIGNATION - S 348 Published NAVD88 330.193 m

NGVD 29 (??/??/92) 330.379 m

There are a set of old benchmarks still standing. These are made of the same materials as monuments the Army used locally, huge and heavy 6" cast iron pipes with caps and stamped with the elevation. They were set prior to the surveys that created NGVD29. They are roughly 10 feet higher than an NGVD29 elevation when located using NGVD29. How they were determined I never researched but we did use them as control points when we could since they are very stable. Then NAVD88 was introduced and lifted 29 up 2.5', but I also never got much of an explanation how the shift was determined, much like the early monuments, it just seemed to happen unlike NGVD29 which has so much easily available history. 

During a seminar I attended concerning the new data, the presenter kept repeating that it's not NGVD29. It seems they were getting flack that they were simply returning to 29. I hadn't even considered that, I just figured it was random that in our location 29 and 2022 were so close. It's interesting to hear how other locations are changing.