The City and Borough of Juneau (pron.: //) is a unified municipality located on the Gastineau Channel in the panhandle of the U.S. state of Alaska and the 2nd largest city in the United States by area. It has been the capital of Alaska since 1906, when the government of the then-District of Alaska was moved from Sitka as dictated by the U.S. Congress in 1900. The municipality unified on July 1, 1970, when the city of Juneau merged with the city of Douglas and the surrounding Greater Juneau Borough to form the current home rule municipality.
The area of Juneau is larger than that of Rhode Island and Delaware individually and almost as large as the two states combined. Downtown Juneau is nestled at the base of Mount Juneau and across the channel from Douglas Island. As of the 2010 census, the City and Borough had a population of 31,275. As of July 2011 the population estimate from the United States Census Bureau is 32,164.
Gastineau Channel is a channel between the mainland of the U.S. state of Alaska and Douglas Island in the Alexander Archipelago of southeastern Alaska. It separates Juneau on the mainland side from Douglas (now part of Juneau), on Douglas Island. The first European to sight the channel was Joseph Whidbey early in August 1794, first from the south and later from the west. It was probably named for John Gastineau, an English Civil Engineer and Surveyor.
The channel is navigable by large ships only from the southeast as far as the Juneau-Douglas Bridge, approximately 9.7 miles (15.6 km). Between the bridge and Juneau International Airport, approximately 8.1 miles (13.0 km), it is navigable only by smaller craft and only at high tide.
The channel is becoming increasingly unnavigable due to shallow water depths. The two principal causes for this are:
If current trends continue, Gastineau Channel may eventually become dry or unnavigable or both.
During isostatic rebound, the Earth’s lithosphere (crust) is slowly rising due to buoyant forces, following the removal of a large mass on the surface. This can be likened to an ice cube floating in a glass of water with a penny sitting on top. The weight of the penny makes the ice cube float lower, similar to the immense weight of a glacier on top of the lithosphere. When the penny (glacier) is removed, the ice cube (lithosphere) “rebounds” and floats slightly higher. In the geologic case, this scenario happens very slowly. Rates of isostatic rebound throughout SE Alaska vary from 0.1 to 1.5 inches/year depending on glacial history. The approximate rebound rate in the Juneau area is 0.25 to 0.5 inches/year.