In earlier times, the Ahtna Alaska Natives roamed the Copper River Valley in search of fish and game, both of which are usually plentiful there.
Ahtna now live in several communities around Glennallen.
In 1899, the U.S. Army built a pack trail for summer use between the port of Valdez and Eagle, which passed through the Copper River Valley.
In the early 20th century, the trail was widened and became the Richardson Highway.

During World War II, the United States built a series of military bases in Alaska, primarily for the purpose of supplying aircraft and other war material to Russia by way of Alaska and the Russian Far East as part of the Lend-lease program.
 This made it difficult for the Germans to the west and the Japanese to the south of Russia to interfere with the supply operation.
 As part of this operation, highways were built to supply the bases.
 The major highway project of this effort was the Alaska Highway from Dawson Creek, British Columbia, Canada to the existing Richardson Highway at Delta Junction, Alaska and thus to Fairbanks via the Richardson Highway.
 Another project was the Glenn Highway, which connected Anchorage, Alaska's largest city, with the Richardson Highway, and thus with the rest of Alaska, Canada, and the then-48 United States.

Construction for the Glenn Highway began at a camp on the Richardson Highway in the Copper River Valley named Glennallen after two U.S. Army explorers of the late 19th century: Capt.
Edwin Glenn and Lt.
Henry T. Allen.
The highway was completed in 1945.
Glennallen developed as a small community around the site of the camp.
It became a commercial center for motor traffic along the Glenn and Richardson highways.
 It is one of the few communities in the region that was not built on the site of a Native village.

During the 1950s and 1960s, another highway, the Tok Cut-Off, was constructed from a point 15 miles north of Glennallen to the community of Tok, 135 miles east on the Alaska Highway.
This enhanced Glennallen as a commercial center.
Also, in 1956, a Jesuit school, Copper Valley School, was opened.
This facility increased the population considerably by bringing to the region a number of staff and students from Holy Cross Mission in western Alaska.
In 1961 "Glenallen" was officially renamed "Glennallen" by the US Postal Service, adding the extra 'n'.

Glennallen's economy grew with the construction of the Trans-Alaska Pipeline System from 1975–1977 and the continuing service needs of the pipeline.
The economy of the area was negatively impacted by the construction of the George Parks Highway, which connected Anchorage to Denali National Park and Fairbanks along the Alaska Railroad route, bypassing Glennallen.
In earlier times, the Ahtna Alaska Natives roamed the Copper River Valley in search of fish and game, both of which are usually plentiful there. Ahtna now live in several communities around Glennallen. In 1899, the U.S. Army built a pack trail for summer use between the port of Valdez and Eagle, which passed through the Copper River Valley. In the early 20th century, the trail was widened and became the Richardson Highway.
During World War II, the United States built a series of military bases in Alaska, primarily for the purpose of supplying aircraft and other war material to Russia by way of Alaska and the Russian Far East as part of the Lend-lease program.  This made it difficult for the Germans to the west and the Japanese to the south of Russia to interfere with the supply operation.  As part of this operation, highways were built to supply the bases.  The major highway project of this effort was the Alaska Highway from Dawson Creek, British Columbia, Canada to the existing Richardson Highway at Delta Junction, Alaska and thus to Fairbanks via the Richardson Highway.  Another project was the Glenn Highway, which connected Anchorage, Alaska's largest city, with the Richardson Highway, and thus with the rest of Alaska, Canada, and the then-48 United States.
Construction for the Glenn Highway began at a camp on the Richardson Highway in the Copper River Valley named Glennallen after two U.S. Army explorers of the late 19th century: Capt. Edwin Glenn and Lt. Henry T. Allen. The highway was completed in 1945. Glennallen developed as a small community around the site of the camp. It became a commercial center for motor traffic along the Glenn and Richardson highways.  It is one of the few communities in the region that was not built on the site of a Native village.
During the 1950s and 1960s, another highway, the Tok Cut-Off, was constructed from a point 15 miles north of Glennallen to the community of Tok, 135 miles east on the Alaska Highway. This enhanced Glennallen as a commercial center. Also, in 1956, a Jesuit school, Copper Valley School, was opened. This facility increased the population considerably by bringing to the region a number of staff and students from Holy Cross Mission in western Alaska. In 1961 "Glenallen" was officially renamed "Glennallen" by the US Postal Service, adding the extra 'n'.
Glennallen's economy grew with the construction of the Trans-Alaska Pipeline System from 1975–1977 and the continuing service needs of the pipeline. The economy of the area was negatively impacted by the construction of the George Parks Highway, which connected Anchorage to Denali National Park and Fairbanks along the Alaska Railroad route, bypassing Glennallen.
Glennallen, Alaska