Glennallen is located in the continental climate zone, with long, cold winters, and relatively warm summers. The mean temperature in January is -10°F (-23°C); in July, 56°F (13°C). 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 1800s.

Glennallen is the supply hub of the Copper River region. Local businesses serve area residents and tourism from the Glenn Highway traffic, supplies and services, schools and medical care. The Glenn/Tok Cutoff and Richardson Highways provide year-round road access to other areas of the state.Glennallen is known for its outstanding scenery and great fishing. If you spend time in communities like this you will understand one of Alaska's biggest assets, its people. Glennallen is the center of the Copper River Basin one of Alaska's premier outdoor recreation areas.