Isabel Pass

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Mountain pass of Alaska, US

title: "Isabel Pass" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["mountain-passes-of-alaska", "landforms-of-copper-river-census-area,-alaska"] description: "Mountain pass of Alaska, US" topic_path: "general/mountain-passes-of-alaska" source: "https://en.wikipedia.org/wiki/Isabel_Pass" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Mountain pass of Alaska, US ::

::data[format=table title="Infobox mountain pass"]

Field	Value
name	Isabel Pass
photo	File:Gulkanaglacier.JPG
photo_caption	Gulkana Glacier seen from Isabel Pass
elevation_ft	3242
traversed	Richardson Highway
location	Copper River Census Area, Alaska, U.S.
range	Alaska Range
map	USA Alaska
map_caption	Alaska
label	Isabel Pass
coordinates
topo	USGS Mount Hayes A-4 NE
::

Isabel Pass (sometimes Delta River Pass) is a 40 mile long gap in the eastern section of the Alaska Range which serves as a corridor for the Richardson Highway about 11 miles from Paxson. It is named after Isabelle Barnette, the wife of E. T. Barnette, who helped found Fairbanks. The pass separates four regions, the Tanana Valley to the north, the Delta Mountains to the east, Copper River Basin to the south, and the Hayes Range to the west.

It is one of three highway passes of the Alaska Range, the others being Windy Pass for the George Parks Highway and Mentasta Pass for the Tok Cut-Off.

Geography

Isabel Pass is also known as the Delta River Valley or the Delta River Pass. Castner Glacier is located on its southern end.

It is one of the drainage divides of the Alaska Range.

The area is also geologically active. The Denali Fault approximately bisects the pass, near Miller Creek, just south of Canwell Glacier. There is also evidence of jökulhlaups caused by surging glaciers temporarily damming the Delta River and/or its tributaries. Rain driven flash flooding and landslides are also known to occur.

History

Before the 19th Century

Isabel Pass was formed predominately by the Delta River, with intermittent contribution from Phelan Creek, in the early Oligocene as the Alaska Range was beginning to be uplifted.

The pass is an important connection between the Ahtna and the Tanana people. Historically, it was a place for trade between the two groups, where the Ahtna would bring copper sourced along the Copper River and seashells traded from the coast to the Tanana to trade for their furs. Trade usually occurred in late summer, where abundant caribou attracted many people. Additionally, Ahtna and Middle Tanana place names of the surrounding area describe land features formed by ice that no longer exists, which suggests that they have been living in the area since at least the last ice age:

River drainages. |James Kari}}

19th Century Onwards

Starting in the late 1880s to mid 1890s, gold discoveries north of the Alaska Range in the Fortymile Mining District, near Circle, and in the western Yukon, among other areas, put pressure on the US Congress to explore Alaska. In March of 1898, the US Department of War funded three expeditions to explore Southcentral Alaska. Edwin Glenn led the expedition ordered to explore from Prince William Sound to Cook Inlet for routes between the Susitna and Copper rivers then northward to the Tanana River. Attached to the expedition was geologist Walter Mendenhall from the USGS. The party was the first recorded non-natives to cross the pass, however they turned around 15 to 20 miles short the Tanana River due short supplies and lateness of the season.

This route received little attention at the time. Speaking about his experiences ten years later, Lieutenant Joseph Castner said:

The founding of Fairbanks in 1901 began non-native interest in Isabel Pass. Sometime in the spring of 1902, E.T. and Isabelle Barnette crossed the pass on their way to Valdez and onto Puget Sound to purchase supplies for the newly formed city. The pass was then named after Isabelle, although it was spelled incorrectly. By 1903, horses were being used to haul supplies and mail over the pass, replacing sled dogs.

Very soon after the establishment of the trail, roadhouses were built along, although many faced difficulties keeping them profitable. In general, the roadhouses along the pass proved to be invaluable to travelers, providing shelter from strong winter storms. Yost's Roadhouse, first known as McCallum's Roadhouse, opened at the northern end of Isabel Pass at the confluence of Phelan Creek and McCallum Creek in 1905 at an elevation of 2,897 feet. Another roadhouse was built roughly 20 miles north in 1904, known as Miller's Roadhouse. Rapids Roadhouse, later Black Rapids Roadhouse, started in 1902-1903 as just a tent, but a two story log building was built soon afterward. At the northern end of the pass, Donnelly's Roadhouse started in 1906, which was among the most popular. Several other roadhouses existed in the area, either as tents or cabins, but they had uncertain distances between points and were very short lived. All of roadhouses in the area were closed by 1930.

In 1903, Lieutenant William Mitchell, Judge James Wickersham, and several Fairbanks residents testified to a senatorial party visiting Alaska, pressuring them for transportation infrastructure. By early 1905, Major Wilds Richardson was appointed by President Teddy Roosevelt to supervise construction of an all-season wagon road from Valdez to Fairbanks, which was completed in 1910 .

The pass came under the soil and water conservation of the Salcha-Big Delta Soil and Water Sub-District in 1950, known today as the Salcha-Delta Soil and Water Conservation District. The highway going through the pass remained gravel until it was paved in 1955 and provided year round travel. The Northern Warfare Training Center was established at Black Rapids in 1956, near the middle of the Isabel Pass.

In the late 1970s, the Trans-Alaska Pipeline was built through the pass. The camp situated at Isabel Pass was also the largest, outside of the main camp at Valdez, during pipeline construction, with 1,652 beds.

The 2002 Denali earthquake struck the region. Landslides occurred near the pass around the fault line, but most were within 30 km of the fault. Soil liquefaction was observed south of the fault line which caused damage to buildings. Around the fault crossing there was localized sand blows and minor fissures.

In mid July of 2022, heavy rain in throughout the pass caused flash flooding and mudslides, leading the closure of the Richardson Highway. Five inches of rain fell at Black Rapids Roadhouse on July 10, which washed out one bridge and damaging several others. Internet and cell phone interruptions were also reported due to a damaged fiber optic cable. On July 21, Governor Mike Dunleavy declared a state disaster, with costs associated with repairing the damages to be over $10 million.

References

{{Cite gnis. 1403945. Isabel Pass
Fred H. Moffit. (1954). "Geology of the eastern part of the Alaska Range and adjacent area". US Department of the Interior, Geological Survey.
"Strain Accumulation Along the Denali Fault at the Nenana River and Delta River Crossings, Alaska". American Geophysical Union.
Troy L. Péwé. (1953). "MULTIPLE GLACIATION IN ALASKA". USGS.
(1900). "Twentieth annual report of the United States Geological Survey, 1898-1899: Part VII - explorations in Alaska in 1898". Alaska Department of Natural Resources Geological and Geophysical Surveys.
(December 1983). "River Management Plan: Delta River". U.S. Department of the Interior.
(2014). "Roadside Geology of Alaska". Mountain Press Publishing Company.
"The galloping glacier's recent dramas". University of Alaska Fairbanks Geophysical Institute.
"Glacier Dammed Lakes and Outburst Floods in Alaska". United States Geological Survey.
(May 2020). "Uninhabited And Free From Work: An Environmental And Federal Land-use Policy History Of Glacial Lake Atna Wilderness, Alaska".
(1983). "Where Raven Stood". University of Alaska Fairbanks.
(2019). "The Resilience of Dene Generative Geography, Considering" the Nen'Yese'Ensemble."". Alaska Journal of Anthropology.
(June 1983). "Alaska Road Commission Historical Narrative". State of Alaska Department of Transportation and Public Facilities.
"History of the Valdez Trail". US National Park Service.
"Isabelle Cleary Barnette - The First Lady of Fairbanks 1875-1942". University of Alaska Anchorage.
"Valdez-Fairbank Trail, a lifeline for early Interior Alaskans".
"The Trail: The Story of the Historic Valdez-Fairbanks Trail that Opened Alaska's Vast Interior". Trapper Creek Museum.
(1910). "The Valdez-Fairbanks trail : the story of a great highway : the Tanana Valley - Valdez, the gateway to an empire : a guide for the Alaska traveler". Alaska Pub. Co..
(2017). "Historic Roads of Alaska: Driving the History of the Last Frontier". : Alaska Department of Natural Resources, Office of History and Archaeology and Interpretation and Education, Alaska State Parks.
"About- Salcha-Delta Soil and Water Conservation District".
(2007). "The Facts: Trans Alaska Pipeline System". Alyeska Pipeline Service Company.
(16 Apr 2004). "Geotechnical Observations of the November 3, 2002 M7.9 Denali Fault Earthquake". International Conference on Case Histories in Geotechnical Engineering.
(12 July 2022). "Flash flooding closes stretch of Richardson Highway". Alaska Public Media.
(14 July 2022). "Flood damage along Richardson Highway disrupts trucking, limits internet and cell service". KUAC.
Tessen, Danielle. "Richardson Washout Response".
Cole, Terrence. ''Crooked Past: The History of a Frontier Mining Camp: Fairbanks, Alaska''. Fairbanks. University of Alaska Press, 1984. Reprinted 1991.

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