Seems like a simple question, but this issue has been bantered about many times here on the Zone with many different answers and explanations. Not sure if this article was posted or not, but it makes a good conversation starter.

Exactly How High is Mt. Whitney?

The National Geodetic Survey provides the current official answer.
Here's the source:
https://www.ngs.noaa.gov/NGSDataExplorer/
Here's the info:
https://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=GT1811
Here's how to read it:
https://www.ngs.noaa.gov/DATASHEET/dsdata.pdf

This is the top of the data record generated today:

PROGRAM = datasheet95, VERSION = 8.12.5.3
1 National Geodetic Survey, Retrieval Date = JULY 17, 2019
GT1811 ***********************************************************************
GT1811 DESIGNATION - WHITNEY
GT1811 PID - GT1811
GT1811 STATE/COUNTY- CA/INYO
GT1811 COUNTRY - US
GT1811 USGS QUAD - MOUNT WHITNEY (1994)
GT1811
GT1811 *CURRENT SURVEY CONTROL
GT1811 ______________________________________________________________________
GT1811* NAD 83(1992) POSITION- 36 34 42.89133(N) 118 17 31.18182(W) ADJUSTED
GT1811* NAD 83(1992) EPOCH - 1991.35
GT1811* NAVD 88 ORTHO HEIGHT - 4421.0 (meters) 14505. (feet) VERTCON
GT1811 ______________________________________________________________________
GT1811 GEOID HEIGHT - -25.216 (meters) GEOID12B
GT1811 LAPLACE CORR - -8.54 (seconds) DEFLEC12B
GT1811 HORZ ORDER - SECOND
GT1811
GT1811.The horizontal coordinates were established by classical geodetic methods
GT1811.and adjusted by the National Geodetic Survey in March 1994.
GT1811.
GT1811.The NAVD 88 height was computed by applying the VERTCON shift value to
GT1811.the NGVD 29 height (displayed under SUPERSEDED SURVEY CONTROL.)
GT1811
GT1811.Significant digits in the geoid height do not necessarily reflect accuracy.
GT1811.GEOID12B height accuracy estimate available here.
GT1811
GT1811.The Laplace correction was computed from DEFLEC12B derived deflections.
GT1811
GT1811. The following values were computed from the NAD 83(1992) position.
GT1811
GT1811; North East Units Scale Factor Converg.
GT1811;SPC CA 4 - 638,407.861 2,063,362.492 MT 0.99994110 +0 25 20.6
GT1811;SPC CA 4 - 2,094,509.79 6,769,548.44 sFT 0.99994110 +0 25 20.6
GT1811;UTM 11 - 4,048,901.365 384,409.209 MT 0.99976461 -0 46 12.1
GT1811
GT1811! - Elev Factor x Scale Factor = Combined Factor
GT1811!SPC CA 4 - 0.99931061 x 0.99994110 = 0.99925175
GT1811!UTM 11 - 0.99931061 x 0.99976461 = 0.99907538
GT1811
GT1811: Primary Azimuth Mark Grid Az
GT1811:SPC CA 4 - WHITNEY AZ MK 147 09 47.4
GT1811:UTM 11 - WHITNEY AZ MK 148 21 20.1
GT1811
GT1811_U.S. NATIONAL GRID SPATIAL ADDRESS: 11SLA8440948901(NAD 83)
GT1811
GT1811|---------------------------------------------------------------------|
GT1811| PID Reference Object Distance Geod. Az |
GT1811| dddmmss.s |
GT1811| GT1812 MT WHITNEY CAIRN 5.610 METERS 01633 |
GT1811| GT1813 WHITNEY 5.530 METERS 01708 |
GT1811| GT0238 K 72 3.805 METERS 03645 |
GT1811| GT1801 CORCORAN MOUNTAIN APPROX. 7.7 KM 1422438.0 |
GT1811| DA9453 WHITNEY AZ MK 1473508.0 |
GT1811| GT1808 MT WHITNEY SMITHSONIAN HOUSE 26.000 METERS 25707 |
GT1811| GT0239 U 43 3.004 METERS 32209 |
GT1811| GT1807 MT KEITH APPROX.14.3 KM 3410702.2 |
GT1811| GT1809 PLAQUE NEAR WHITNEY 3.002 METERS 35737 |
GT1811| GT1810 14502 2.982 METERS 35753 |
GT1811|---------------------------------------------------------------------|
GT1811
GT1811 SUPERSEDED SURVEY CONTROL
GT1811
GT1811 NAD 83(1986)- 36 34 42.88215(N) 118 17 31.17367(W) AD(1984.00) 2
GT1811 NAD 27 - 36 34 43.11320(N) 118 17 27.85660(W) AD( ) 2
GT1811 NGVD 29 (07/19/86) 4419.1 (m) 14498. (f) VERT ANG
GT1811
GT1811.Superseded values are not recommended for survey control.
GT1811
GT1811.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums.
GT1811.See file dsdata.pdf to determine how the superseded data were derived.
GT1811


Dale B. Dalrymple

The short version is 14,505' today.

Dale B. Dalrymple

14508 on datasheet 1810

My T-Shirts say 14,508 feet.

That's official enough for my ego.

Must be the recent earthquakes that have pushed the peak up a few more ft

Is Mt. Whitney rising or is the Owens Valley sinking?

I just ran VERTCON myself and found the datum conversion to be +6.13 ft going from the old retired datum NGVD29 to the current datum NAVD88. This is key information and it would be helpful if these NGS data sheets indicated the datum differential, but I don't see it. They do a geoid height adjustment, but that's more complicated to understand.

So just converting from the old datum (NGVD29) to the new datum (NAVD88) increases the original elevation by +6.13 ft. That datum shift is pretty much the same for every elevation point in the general area. That explains most of the confusion about how the elevation suddenly went up so much. But it doesn't explain the various new elevations that are popping up. The other confusion comes from deciding which elevation to convert? That's the historical part of the problem. Various elevations are stated from various surveys. Which one is best?

There are two NGS DATASHEETS for Mt. Whitney (maybe more) GT1810 and GT1811. GT1811 seems better to me. For one, it appears to be more recent, based on the numbering scheme. But more importantly, GT1811 is based on converting a previous survey control to the new datum. In contrast, GT1810 scales the height from surrounding benchmarks used to develop the 1994 topo Quad Mt Whitney. The quality of converting a single good survey benchmark (GT1811) should be better than interpolating from topo data (GT1810).

There are two important survey monuments used for GT1811 DATASHEET, one located on a rock stamped 14502. The rock is 3.5 ft tall. This monument is apparently the highest point that we're interested in. But the best horizontal control on the summit seems to be the Whitney 1950 monument (above 10 ft north of 14502). GT1811 adjusts horizontally from Whitney 1950 and Monument 14502 to improve the horizontal control, but that doesn't really affect the elevation at 14502.

If you add 6.13 ft to 14502 you get 14508 ft NAVD88. If you subtract the height of the rock, you get 14505 ft. The rock height could be an explanation for the difference between 14508 and 14505. It seems reasonable to think interpolation could miss a boulder, but that's just speculation.

There are other elevations to convert, just to add to the confusion. The National Park Service 1930 plaque puts it at 14,496.811. Add +6.13 ft to convert to the new datum, you get 14,502.94 in the new NAVD88 datum.

At this point in time, the latest NGS Datasheet seems to be GT1811, which lists Whitney at 14,505 ft . Unless there is a newer DATASHEET I'm not aware of, that seems to be the "official" elevation.

I hope this sheds some additional light on the subject. Go Figure.

Thanks for that, Mr. SierraNevada. I appreciate the nicely written explanation.

Now if you could only spend some time explaining the geoid height adjustment, it would be appreciated. I've never come across anything that explains it simply enough that my lame brain could understand.

Another thing to consider is that these elevation are based on older surveys and techniques and than adjusted to the "current" 1988 datum. I was told by a senior NGS employee for the western states that none of the 14ers have elevation observations done with survey grade GPS receivers. NGS requires a 4 hours continuous observation on a point for them to post process and publish the data. This would surely create new elevations for the benchmarks. I had dreams of making observations on some of the peaks but I wasn't sure if I could wait 4 hrs and I didn't want to throw out my t shirts....

CLIMB THE HIGHEST MOUNTAIN, BUT HOW HIGH IS MT. WHITNEY?

"......The National Park Service placed the following plaque: “Mount Whitney Elevation 14,496.811 feet. John Muir Trail-High Sierra September 5, 1930........"

Article:

https://angeles.sierraclub.org/news/blog/2012/10/climb_highest_mountain_how_high_mt_whitney

When I went up Mount Evans in Colorado from Guanella Pass I found three guys at the top who were there for three days of data collection, but it was only about 100' vertical down to their van in the paved parking lot. They weren't wearing t-shirts.

Dale B. Dalrymple

I'm surprised that no one has gained access to drive to the top of White Mt and get that one done.

Good info, and interesting topic. I heard from a good source that there will be a new measurement in 2022. Don't forget about the Height Above the Elipsoid (HAE). "Sea Level" is not a straight forward value. I'm not sure what method they plan to use in the future. And I have not studied extensively recently. Looking forward to hearing more about this for sure. I've heard that the White Mountains are rising and may overtake Whitney some day
This may be way in the future, not on our lifetime scale.

On this subject...I see varying elevations for Trail Crest, 13,777ft from past notes and articles or 13,600ft from the sign. Which one is correct? Or are these measured at different spots along that ridge above the chute or switchbacks and both correct just measured from different spots?

If I recall past discussions, I think the 13,777 was considered a mapping or printing error.

...In fact, I went searching, and the late Wayne Pyle, (a true mapping enthusiast -- he mapped the 99 switchbacks )
wrote this in this topic: My epic photo of the 97 switchbacks (at night!)

Interesting thanks Steve!

I actually am looking at the map I got back then from the ESIAVC and it has 13,777ft listed for elevation of Trail Crest! That was from our first trip in 2007. I'm not sure how to post that pic here...?

So there's the "official" evidence: 13777 at Trail Crest.

From memory, I sure don't think Discovery Pinnacle, (lowered to 13,750), is 150' higher than Trail Crest. It's just a short walk up to the top.

ah yes. Thanks Steve.

Now when is someone gonna say Whitney is actually 15,000ft??

Picture at Trail Crest from 1964. From Paul W, pictures from a trip his father and brother took:

Ah. cool pic. I seem to remember seeing a sign with that elevation somehere. Was there another one placed somewhere? When was that removed?

Just got done watching the movie, "High Sierra" starring Humphrey Bogart. In this 1941 picture, if you haven't seen it, the movie has several scenes in Lone Pine and the road to the Portal.

Anyway, at the beginning of the movie, Bogart is at a gas station with Mt Whitney in the background. The attendant mentions Mt Whitney is the highest peak in the USA at 14,501 feet...... again, 1941.

paul

This could be. I would imagine that the elevation of Trail Crest is the actual elevation at the notch itself (ie the entrance into Sequoia NP). The trail is, of course, somewhat higher at the top of the switchbacks. But I’m not sure whether it is 177ft higher when it starts to descend to Trail Crest.