 Interstate 90 | |
|---|---|
 Map of the contiguous United States with I-90 highlighted in red | |
| Route information | |
| Length | 3,021.22 mi[1] (4,862.18 km) |
| Existed | 1956–present |
| NHS | Entire route |
| Major junctions | |
| West end |  SR 519 in Seattle, WA |
| |
| East end |   Route 1A/Logan International Airport in Boston, MA |
| Location | |
| Country | United States |
| States | Washington, Idaho, Montana, Wyoming, South Dakota, Minnesota, Wisconsin, Illinois, Indiana, Ohio, Pennsylvania, New York, Massachusetts |
| Highway system | |
Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at 3,021 miles (4,862 km). It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain West, Great Plains, Midwest, and the Northeast, ending in Boston, Massachusetts. The highway serves 13 states and has 15 auxiliary routes, primarily in major cities such as Chicago, Cleveland, Buffalo, and Rochester.
I-90 begins at Washington State Route 519 in Seattle and crosses the Cascade Range in Washington and the Rocky Mountains in Montana. It then traverses the northern Great Plains and travels southeast through Wisconsin and the Chicago area by following the southern shore of Lake Michigan. The freeway continues across Indiana and follows the shore of Lake Erie through Ohio and Pennsylvania to Buffalo. I-90 travels across New York by roughly following the historic Erie Canal and traverses Massachusetts, reaching its eastern terminus at Massachusetts Route 1A near Logan International Airport in Boston.
The freeway was established by the Federal-Aid Highway Act of 1956, replacing a series of existing U.S. highways that had been preceded by local roads and auto trails established in the early 20th century. I-90 was numbered in 1957, reflecting its status as the northernmost transcontinental route of the system, and construction was underway on several sections with funding from the Federal-Aid Highway Act.
The route also incorporates several toll roads that predate the Interstate Highway System, including the Jane Addams Memorial Tollway, Indiana Toll Road, Ohio Turnpike, New York State Thruway, and the Massachusetts Turnpike. These toll roads opened in the 1950s and were followed by toll-free sections in Pennsylvania and Wisconsin that were finished in the 1960s. The Midwestern sections of I-90 were fully completed in 1978, and most of the route between Seattle and South Dakota opened by 1987. The final section, near the western terminus in Seattle, opened in September 1993; an eastern extension in Boston was completed in 2003 as part of the Big Dig project.
- ^ "Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways as of December 31, 2021". Route Log and Finder List. Federal Highway Administration. January 26, 2022. Archived from the original on April 22, 2012. Retrieved February 10, 2022.