Interstate 90

Interstate 90
source
Country	USA
Route	90
Length mi	3020.54
Length km	4861.09
Direction a	West
Terminus a	SR 519 / 4th Avenue in Seattle, Washington
Direction b	East
Terminus b	MA 1A in Boston, Massachusetts
States	Washington, Idaho, Montana, Wyoming, South Dakota, Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, New York, Massachusetts
System	Interstate Highway System

Interstate 90 is a major transcontinental highway in the United States, forming the longest segment of the Interstate Highway System. Spanning approximately 3,021 miles, it connects the Pacific and Atlantic coasts, running from Seattle, Washington to Boston, Massachusetts. The route traverses diverse landscapes, including the Cascade Range, the Great Plains, and the Appalachian Mountains, serving as a vital corridor for commerce and travel.

Route description

Beginning at an interchange with SR 519 near the Port of Seattle, the highway travels east across Washington, passing through the Snoqualmie Pass in the Cascade Range and the Columbia River basin. In Idaho, it follows the path of the historic Mullan Road near Coeur d'Alene before entering Montana, where it crosses the Continental Divide at Homestake Pass and skirts the northern edge of Yellowstone National Park. The route bisects the Great Plains in Wyoming and South Dakota, passing near landmarks like Mount Rushmore and the Badlands National Park. East of the Mississippi River, it serves major metropolitan areas including Minneapolis–Saint Paul, Chicago, Cleveland, and Buffalo, before terminating at Logan International Airport in Boston.

History

The highway's development was authorized under the Federal-Aid Highway Act of 1956, championed by President Dwight D. Eisenhower. Its alignment often followed older transportation corridors, such as the Mullan Road, the Chicago and North Western Railway, and the New York State Thruway. Significant engineering projects included the construction of the Latah Creek Bridge in Spokane, the Deep Creek Tunnel in Montana, and the massive Jane Addams Memorial Tollway reconstruction in Illinois. The final segment to open was the Central Artery in Boston, part of the larger Big Dig project overseen by the Massachusetts Department of Transportation.

Major intersections

From west to east, key junctions include Interstate 5 in Seattle, Interstate 15 near Butte, and Interstate 29 in Sioux Falls. In the Midwest, it intersects Interstate 35 in Minneapolis and Interstate 94 in Tomah. Critical eastern interchanges are with Interstate 65 and Interstate 80/94 in Gary, Indiana, Interstate 71 in Cleveland, and Interstate 79 near Erie, Pennsylvania. In New York, it meets the New York State Thruway (Interstate 87) and converges with Interstate 84 near Newburgh before ending at MA 1A in Boston.

Auxiliary routes

Several three-digit auxiliary routes serve metropolitan areas along the corridor. These include I-190 providing access to O'Hare International Airport in Chicago, and I-290 connecting to the city's western suburbs. In Ohio, I-480 forms a southern bypass of Cleveland, while Interstate 990 in New York is the highest-numbered auxiliary route in the system, serving Amherst. In Massachusetts, I-190 links to Worcester and I-290 provides a direct route into Boston.

See also

* List of Interstate Highways * U.S. Route 20 * Pan-American Highway * Eisenhower Tunnel * Massachusetts Turnpike * Indiana Toll Road * Ohio Turnpike * New York State Thruway

Category:Interstate 90 Category:Transportation in the United States