The Great Northern Tunnel is a 1 miles (1.6 km) double tracked railway tunnel

Tunnel

A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

 under downtown Seattle, Washington

Seattle, Washington

Seattle is the county seat of King County, Washington. With 608,660 residents as of the 2010 Census, Seattle is the largest city in the Northwestern United States. The Seattle metropolitan area of about 3.4 million inhabitants is the 15th largest metropolitan area in the country...

, completed by the Great Northern Railway in 1905, and now owned by the BNSF Railway

BNSF Railway

The BNSF Railway is a wholly owned subsidiary of Berkshire Hathaway Inc., and is headquartered in Fort Worth, Texas. It is one of seven North American Class I railroads and the second largest freight railroad network in North America, second only to the Union Pacific Railroad, its primary...

 and is on its Scenic Subdivision

Scenic Subdivision

The Scenic Subdivision or Scenic Sub is a railway line running about from Seattle, WA to Wenatchee, WA. It is operated by BNSF Railway as part of their Northern Transcon and contains the record setting Cascade Tunnel as well as the final spike completion site, in 1893, at Scenic, WA, for the whole...

. At the time it was built, the tunnel was the highest and widest in the United States at 28 feet (8.5 m) high and 30 feet (9.1 m) wide.

The southern portal is just north of King Street Station

King Street Station (Seattle)

King Street Station is a train station in Seattle, Washington. Located between South King and South Jackson streets and Second and Fourth Avenue South in the Pioneer Square neighborhood of Seattle, the station is just south of downtown...

. The northern portal is located in Victor Steinbrueck Park, below the Alaskan Way Viaduct

Alaskan Way Viaduct

The Alaskan Way Viaduct, completed on April 4, 1953, is a double-decked elevated section of State Route 99 that runs along the Elliott Bay waterfront in Seattle's Industrial District and downtown Seattle. It is the smaller of the two major north–south traffic corridors through Seattle ,...

, between Virginia and Pine Streets. The Downtown Seattle Transit Tunnel passes four feet below the Great Northern Tunnel.

Freight and passenger trains use this tunnel today, including Amtrak

Amtrak

The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...

 routes to Chicago

Chicago

Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...

 ("Empire Builder

Empire Builder

The Empire Builder is a passenger train route operated by Amtrak in the Midwestern and Northwestern United States. It is Amtrak's busiest long-distance route and busiest daily train, carrying more than 500,000 travelers annually since 2007. Overall, it is the railroad's 10th-busiest line. Before...

") and Vancouver, B.C.

Vancouver

Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...

 ("Cascades

Amtrak Cascades

The Amtrak Cascades is a passenger train route operated by Amtrak in partnership with the states of Washington and Oregon in the Pacific Northwest of the United States and the province of British Columbia in Canada...

"), as well as Sound Transit

Sound Transit

Sound Transit has been the popular name of Washington state's Central Puget Sound Regional Transit Authority since September 19, 1999. It was formed in 1996 by the Snohomish, King, and Pierce County Councils...

's Seattle-Everett

Everett, Washington

Everett is the county seat of and the largest city in Snohomish County, Washington, United States. Named for Everett Colby, son of founder Charles L. Colby, it lies north of Seattle. The city had a total population of 103,019 at the 2010 census, making it the 6th largest in the state and...

 "Sounder

Sounder Commuter Rail

Sounder commuter rail is a regional rail service operated by BNSF on behalf of Sound Transit. Service operates Monday through Friday during peak hours from Seattle, Washington, north to Everett and south to Tacoma. As of 2011, schedules serve the traditional peak commutes, with most trains running...

" commuter train.