It was declared a National Historic Landmark in 1986.
Development of the mines began immediately. Ore was taken out by pack horses on a trail to Valdez. Political battles over the mining and subsequent railroad were fought in the office of U.S. President Theodore Roosevelt between conservationists and those having a financial interest in the copper.
In 1903, additional financing for the mining came from the Guggenheim family and J.P. Morgan, who formed the Kennecott Copper Corporation in 1903. The corporation and company town were named after Kennicott Glacier, which was situated in the valley below the town. The glacier was named after Robert Kennicott, a naturalist who explored in Alaska in the mid-1800s. Due to a clerical error, the corporation and town used the spelling of "Kennecott" instead of "Kennicott." It is occasionally also seen as "Kennycott."
Kennecott had five mines: Bonanza, Jumbo, Mother Lode, Erie and Glacier. Glacier, which is really an ore extension of the Bonanza, was an open-pit mine and was only mined during the summer. Bonanza and Jumbo were on Bonanza Ridge about 5 km, (3 miles) from Kennecott. The Mother Lode mine was located on the east side of the ridge from Kennecott. The Bonanza, Jumbo, Mother Lode and Erie mines were connected by tunnels. The Erie mine was perched on the northwest end of Bonanza Ridge overlooking Root Glacier about 6 km (4 miles) up a glacial trail from Kennecott. Ore was hoisted to Kennecott via the trams which head-ended at Bonanza and Jumbo. From Kennecott the ore was hauled mostly in 140-pound sacks on steel flat cars to Cordova, 196 rail miles away on the Copper River and Northwestern Railway (CRNW).
In 1925 a Kennecott geologist predicted that the end of the high-grade ore bodies was in sight. The highest grades of ore were largely depleted by the early 1930s. The Glacier Mine closed in 1929. The Mother Lode was next, closing at the end of July 1938. The final three, Erie, Jumbo and Bonanza, closed that September. The last train left Kennecott on November 10, 1938, leaving it a ghost town. In the 27 years of operation, except for 2 1/2 years of shutdown, Kennecott produced 4.625 million tons of ore averaging 13 per cent copper valued at roughly $207,000,000 with an estimated profit of $100,000,000. In addition, the silver by-product from this operation brought in another 4 1/2 to 9 million dollars in revenues.
From 1939 until the mid-1950s, Kennecott was deserted except for a family of three who served as the watchmen until about 1952. In the late 1960s, an attempt was made to reprocess the tailings and to transport the ore in aircraft. The cost of doing so made the idea unprofitable. Around the same time, the company with land rights ordered the destruction of the town to rid them of liability for potential accidents. A few structures were destroyed, but the job was never finished and most of the town was left standing. Visitors and nearby residents have stripped many of the small items and artifacts. Some have since been returned and are held in various archives.
In the 1980s, Kennecott became a somewhat popular tourist destination, as people came to see the old mines and buildings. However, the town of Kennecott was never repopulated. Residents involved in the tourism industry often lived in nearby McCarthy or on private land in the surrounding area. The area was designated a National Historic Landmark in 1986 and the National Park Service acquired much of the land within the Kennecott Mill Town in 1998. The National Park Service is currently stabilizing and rehabilitating many of the mill and town buildings. Some of the structures, as well as surrounding lands, remain under private ownership. Tours of the mill town are available three times a day through a local guide service, St. Elias Alpine Guides.
Popular tourist activities while visiting Kennecott include glacier hiking, ice climbing, and touring the abandoned mill. Visitors may also hike to the abandoned Bonanza, Jumbo and Erie mines, all of which are strenuous full-day hikes, with Erie Mine being a somewhat terrifying scramble along cliffs overlooking the Stairway Icefall. Local guide services offer all of these hikes if you would like some route-finding assistance.
Kennecott is now accessible by air (McCarthy has a 500 m/1,500 foot gravel runway) or by driving on the Edgerton Highway to the McCarthy Road, an unimproved gravel road. The McCarthy Road ends at the Kennicott River and a footbridge is available for pedestrian traffic to McCarthy. From McCarthy, it is 4.5 miles to Kennecott, and shuttles are available.