GNSS-Based Colorado Centennials List

The GNSS-Based Colorado Centennials List

May-June, 2026

Eric Gilbertson, Elijah Gendron, Dylan Kilby, Ben Loftin, Joseph Thompson

Abstract

The Colorado Centennials List, composed of the 100 highest peaks in Colorado with at least 300 ft of prominence, is a popular peakbagging objective in Colorado. The list was originally based on measurements from the USGS quadrangles, but was updated based on Light Detection and Ranging (LiDAR) data in 2021. Based on LiDAR errors, seven peaks were within error bounds of inclusion. For this study, ground surveys were conducted with professional surveying equipment including multiple GNSS (Global Navigation Satellite System) units of these peaks. We found that Crestone Peak and Columbia Point should be removed and East Crestone and Niagara Peaks added to the list. We refer to this list as the GNSS-based Colorado Centennials.

Introduction

The Colorado Centennials is a popular peakbagging list that is a collection of the 100 tallest peaks in Colorado with at least 300ft of prominence. It was first completed by Spencer Swanger in 1977 (Swanger 2010). By 2026 several hundred people had completed the entire list (CMC 2025). The list has evolved over time as more accurate elevation and prominence measurements have been performed. In 1977 the list was based on the most updated USGS quadrangles, which relied on theodolite- and photogrammetry-based measurements. The Quad-Based Centennials list was the accepted list between 1977-2021. A full list of these 100 peaks can be found here: https://peakbagger.com/list.aspx?lid=50083

Between 2018 – 2019 airplane-based LiDAR measurements were taken of the highest mountains of Colorado, and data made publicly available in 2021. For these surveys, the airplane’s elevation and coordinates are known with high accuracy (horizontal one sigma errors 5-15cm, vertical 7.5-22.5cm, May 2007) from onboard GNSS units and inertial measurement units. The plane sends a pulse of light to the ground and measures the time of return to the plane. This time of light travel can be used to calculate the distance from the plane to the ground, which can then be used with the plane’s known position to calculate the elevation and latitude and longitude coordinates of the sampled location on the ground.

These measurements resulted in several peaks being removed from the Centennials list and several added. Dallas Peak and Teakettle Mountain were removed and Arrow and Trinity added based on elevation. The true summit of Mt Buckskin was found to be several hundred feet away along a ridge from the point previously considered the summit. By 2021, the Quad-Based Centennials list had been updated to the LiDAR-Based Centennials list.

LiDAR measurements are not perfect, though, and are subject to errors. Sampled points in a LiDAR survey have nominal horizontal spacing 1.1ft (USGS 2025). However, in practice we have found horizontal spacing can be up to 10ft in mountainous terrain (Gilbertson et al, 2025), and locations between sample points are unmeasured. Summit elevations determined based on manually-processed LiDAR point cloud data for above-treeline summits have vertical errors +/-1.7ft (95% confidence interval) when compared to GNSS measurements (Gilbertson et al, 2025). In rare instances, vertical errors have been found up to 3.1ft (in the case of Crestone Peak). Sources of error in rocky non-vegetated terrain include sharp summits being missed, and unnatural objects being hit and interpreted as ground (objects such as cairns and people).

Based on LiDAR errors, several peaks were within error bounds of inclusion on the list based on prominence or elevation. Columbia Point was within the error bounds of the 300ft prominence requirement. We measured this peak with GNSS in October 2025 to have only 299.6ft of prominence and thus did not qualify for inclusion.

East Crestone was also within error bounds of qualifying based on prominence, and we surveyed it with GNSS in October 2025 (Gilbertson et al. 2025). We discovered that East Crestone was taller than Crestone Peak, and they had a short enough saddle in between that only the taller of the two would have over 300ft of prominence. Thus, Crestone Peak was removed from the Centennials list (and from the 14ers list) and East Crestone was added to the Centennials list (and to the 14ers list).

After Columbia Point and Crestone Peak were removed from the list and East Crestone added, this left five peaks tied for number 100. The peaks with manually-processed LiDAR elevations rounded to the nearest foot were Arrow Peak (#98 13,817ft), Trinity Peak (#99 [tie], 13,816ft), Niagara Peak (#99 [tie], 13,816ft), Teakettle Mountain (#101, 13,815ft), and American Peak (#102, 13,814ft). These were considered tied because they were all within +/-3.1ft of the elevation of the #100 peak, 13,816ft. The next lowest peaks on the list were Obstruction and Dallas, both 13,812ft based on manually-processed LiDAR data.

With this study we aimed to take elevation measurements of these five peaks with sufficient vertical accuracy to determine which qualified as centennial peaks. This would thus establish a GNSS-Based Centennials List. We additionally measured Obstruction Peak to increase confidence in it being too short for inclusion.

Methodology

We brought a Trimble DA2 GNSS unit capable of 0.1ft vertical accuracy or better to each summit and logged data for one hour. We processed data with TrimbleRTX. To determine the summit location, we went to the LiDAR-identified summit location and used a 2.5x Sokkia surveyors sight level to identify the highest rock in the vicinity of this location. We excluded rocks that were obviously human-created cairns.

Eric and Elijah surveyed Arrow Peak and Trinity Peak May 24, 2026. Eric and Dylan surveyed Niagara Peak May 25, and attempted to survey American peak that day, but it was covered in deep snow. Elijah surveyed Teakettle Peak May 25. Joseph surveyed American Peak June 6. Additionally, Eric surveyed Obstruction Point on June 16.

Results

All measurements were processed with TrimbleRTX, with results shown in Table 1 below. Results are reported in NAD83 2011 Epoch 2010 NAVD88 Geoid 18, the current US standard.

Table 1: GNSS-measured elevations for each peak, with sigma for measurement error. Elevations in NAVD88.

Rank	Peak	Elevation (ft)	Sigma (ft)
98	Arrow	13817.8	0.10
99	Niagara	13816.2	0.11
100	Trinity	13815.8	0.12
101	Teakettle	13815.2	0.15
102	American	13814.1	0.08
103	Obstruction	13813.0	0.10

 

Discussion

Teakettle, American, and Obstruction peaks are too short to qualify as Centennial peaks. The summits of Arrow and Obstruction were sharp boulders that were likely missed by LiDAR, meaning LiDAR underestimated their heights. Niagara, American, and Teakettle had flatter summits leading to smaller magnitudes of errors, but still had sharp enough highest points that they were missed by LiDAR, meaning LiDAR underestimated their heights. Interestingly, the LiDAR elevation of Trinity was an overestimate. But since the LiDAR measurement was rounded to the nearest foot, it’s possible it was rounded up, and this led to the overestimate. In general on these kinds of rocky above-treeline peaks, manually-processed LiDAR measurements are underestimates. Measurements of cairns might lead to overestimates, but these can be manually removed based on user experience and pictures. But sharp boulders we still generally be missed by LiDAR, leading to underesimates of height.

LiDAR errors were -0.8ft (Arrow), +0.2ft (Trinity), -0.2ft (Niagara), -0.2ft (Teakettle), -0.1ft (American), -1.0ft (Obstruction).

The next closest peaks above the #100 cutoff has LiDAR-derived elevation of 13,8120ft (Peak UN 13820). This is 4.2ft above the cutoff, so is very likely to indeed be a centennial peak unless LiDAR hit a person or a large cairn on the summit. This does not appear to be the case based on the experience of the authors on the summit of UN 13820, and based on analysis of the LiDAR data.

The next closest peak below the #100 cutoff is Dallas, with manually-processed LiDAR-derived elevation of 13,812ft. This is 3.8ft below the cutoff for inclusion, so it is very unlikely it would get added as a centennial peak unless it had an extremely sharp summit spire that could get missed by LiDAR. Based on the experience of the authors climbing Dallas, though, this is not the case.

Trinity and Teakettle are close enough in elevation that it may appear there is a chance their order could be switched. However, based on the measured sigma and mean values, we calculated there is a 99.8% chance Trinity is taller than Teakettle. This is greater than the standard scientific threshold of 95%, thus we are confident concluding Trinity is number 100 and Teakettle is number 101.

Thus, we can conclude with high confidence that the GNSS Colorado Centennials list is now finalized. The finalized list can be found on peakbagger here: https://www.peakbagger.com/list.aspx?lid=21363

Conclusion

The GNSS-Based Centennials List has been finalized, with all edge cases based on prominence and elevation resolved. The list is now stable and future changes are not anticipated outside of natural events such as landslides.

Data Availability

Raw measurement files (t04 format) can be accessed at:

https://github.com/ericgilbertson1/ColoradoCentennials 

Author Notes

Eric Gilbertson completed the Centennials list in 2020, setting the self-supported Fastest Known Time (33 days). This record still stands as of 2026. Joseph Thompson completed the Centennials list in 2025, and Elijah Gendron completed it in 2026 on Vermillion. Ben Loftin and Dylan Kilby are currently working on completing the Centennials list.

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© 2026, egilbert@alum.mit.edu. All rights reserved.