Interstate 90 (I-90): Route, Length, Tolls and Safety Data

How long is I-90?

Wikipedia puts I-90 at 3,099.74 miles from end to end, the longest of any Interstate. In the January 2026 FHWA Route Log it has only 2,705.99 miles, second to I-80's 2,891.59.

The difference is shared pavement. When two Interstates use the same lanes, the Route Log books those miles to one of them, and on I-90's longest overlaps it books them to the other road. I-90's rows leave out 91.76 miles shared with I-94 in Wisconsin, 15.32 miles shared with I-94 and 16.62 with I-39 in Illinois, 135.6 miles shared with I-80 on the Indiana Toll Road and 142.80 shared with I-80 on the Ohio Turnpike. That is why the table shows Indiana with just 20.75 miles of I-90 when the road crosses the whole state. Counted the way this page's crash rates count them, with Wikipedia's 187.13 miles for Wisconsin and 123.89 for Illinois plus the full Indiana and Ohio overlaps, I-90 comes to 3,095.33 miles, within about 4 miles of Wikipedia's total.

Montana has the most I-90 mileage at 544.70 miles, followed by South Dakota at 412.76 and New York at 386.27. Pennsylvania's 46.37 miles are the shortest state segment once the Indiana overlap is counted. Interstate Guide gives 3,021.22 miles for the whole route, a figure that keeps Wisconsin net of I-94 but counts the Indiana and Ohio miles in full.

Where I-90 starts and ends

The western end is at Washington State Route 519 and 4th Avenue South in Seattle's SoDo district. The eastern end is Massachusetts Route 1A in East Boston, near Logan International Airport, which I-90 reaches through the Ted Williams Tunnel under Boston Harbor.

Heading east from Seattle, the route climbs over Snoqualmie Pass at 3,022 feet and runs through Spokane and northern Idaho, crosses into Montana at Lookout Pass and goes on through Missoula and Butte. East of Butte it tops the Continental Divide at Homestake Pass, 6,329 feet, the highest point on I-90. It continues through Bozeman, Billings and Rapid City, passes Wall near Badlands National Park, and crosses southern Minnesota to La Crosse, Madison, Rockford and Chicago. From there it follows the toll roads to Toledo and Cleveland, the New York Thruway past Buffalo, Rochester, Syracuse, Utica and Albany, and the Massachusetts Turnpike through Springfield to Boston.

Interstate junctions along I-90

Junctions with other main Interstates are listed west to east. I-94 turns up five times. It starts at Lockwood, near Billings, shares I-90's lanes across southern Wisconsin from near Tomah to Madison, rejoins it through Chicago, and meets it again at Lake Station, Indiana, where I-80 takes over as I-90's partner as far as Elyria, Ohio. I-39 and I-80 each appear twice, once where their overlap with I-90 begins and once where it ends.

Fatal crashes on I-90

Fatal crashes on the I-90 mainline killed 608 people from 2020 to 2024, about 122 a year. Over the route's length that comes to 3.9 deaths per 100 route miles each year, well below the Interstate average of 9.5. Only six of the 56 routes long enough to rank have a lower rate. Deaths went from 105 in 2020 to 131 in 2021, peaked at 136 in 2023 and dropped to 109 in 2024.

Illinois stands apart at 11.8 deaths per 100 miles a year, and Cook County, which includes Chicago, had 52 deaths, more than any other county on the route. Cuyahoga County, around Cleveland, was next with 46, followed by Kittitas and King counties in Washington and Big Horn County, Montana. The state rates count shared stretches, so Indiana's is figured over 156.35 miles rather than the Route Log's 20.75.

Read the low rates in Indiana (1.0) and Wisconsin (2.0) with care. Both states share long stretches with another Interstate, and a crash report can carry either number. In Indiana the federal crash file lists 72 deaths on I-80 and 8 on I-90, so most crashes on the shared Toll Road are probably filed under I-80. Among states with no long overlap, Wyoming has the lowest rate at 1.8.

Counties with the most I-90 crash deaths

Bridges on I-90

The 2025 National Bridge Inventory counts 2,602 bridges carrying the I-90 main line, and half were built in 1965 or earlier. Of those, 116 rate Poor, or 4.5 percent, the highest share on any Interstate longer than 1,000 miles. Washington has 40 of them, about one in six of its 246 I-90 bridges. New York and Massachusetts have 23 each.

In Seattle, I-90 crosses Lake Washington to Mercer Island on two floating bridges: the Lacey V. Murrow Memorial Bridge carries eastbound traffic and the Homer M. Hadley Memorial Bridge carries westbound traffic and, since March 28, 2026, Sound Transit's 2 Line light rail trains. The original Murrow bridge sank in November 1990 while it was being renovated, and its replacement opened to eastbound drivers on September 12, 1993. In Cleveland, the 1959 Innerbelt viaduct over the Cuyahoga River was demolished by July 2014 and replaced by the twin George V. Voinovich Bridges, with all lanes open on the new spans by October 24, 2016.

Tolls on I-90

FHWA's January 2023 toll inventory lists eight facilities on I-90, all between the Wisconsin-Illinois line and Boston. West of that line the road is free all the way to Seattle. Heading east, a driver pays on the Jane Addams Memorial Tollway toward O'Hare, rides the free Kennedy and Dan Ryan expressways through Chicago, then pays on the Chicago Skyway, the Indiana Toll Road and the Ohio Turnpike as far as Elyria. I-90 is free through Cleveland and Pennsylvania. The New York State Thruway charges from the Pennsylvania line to Albany, except for free stretches around Buffalo and Albany, and its Berkshire Section continues the tolls to Massachusetts. The Massachusetts Turnpike and the Ted Williams Tunnel, which FHWA lists separately, finish the trip.

Two of the eight are run by private companies under long leases: the Chicago Skyway for 99 years from January 2005 and the Indiana Toll Road for 75 years from 2006. Facility miles in the table describe each road as FHWA files it, which does not always match I-90's share. The Indiana Toll Road's 157.0 miles cover the whole road, most of it shared with I-80, while the Ohio Turnpike's 142.8 miles are only the part I-90 uses of a turnpike that runs 241 miles.

I-90 auxiliary routes

Nine three-digit routes carry I-90's number, every one from I-190 to I-990, and New York has all nine. The longest is I-390 at 76.36 miles, serving Rochester. Between Seattle and Chicago there is only one, a 2.07-mile I-190 into Rapid City. I-190 is a separate road in four states (South Dakota, Illinois, New York and Massachusetts), and I-290 in three, near Chicago, Buffalo and Worcester. I-490 serves both Rochester and Cleveland.

How I-90 was built and extended

Long pieces of I-90 were built as toll roads in the mid-1950s, while the Interstate system was still being set up. The Ohio Turnpike opened in full on October 1, 1955, the New York State Thruway opened in segments from 1954 to 1957, and the Massachusetts Turnpike's original main line was built from 1955 to 1957. The route got its number in 1957, the year after the Federal-Aid Highway Act was signed. Chicago's Dan Ryan Expressway opened on December 15, 1962, billed at the time as the world's widest freeway.

The western states took longer. Minnesota declared its section complete in September 1978, and Wyoming opened its last section in July 1985. In Wallace, Idaho, an elevated bypass opened in September 1991, and the last traffic signal on I-90 came out shortly afterward. Seattle's extension to the present western end went in by stages from 1989 to 1993.

The eastern end was the last to move. The Big Dig extended I-90 3.5 miles through the Fort Point Channel and Ted Williams tunnels to Logan Airport, and the full extension opened on January 18, 2003. For the wider project, see the Big Dig's lessons for American megaprojects.

I-90 traffic and road conditions

For closures, pass reports and crash alerts on I-90 today, use the traveler information site for the state you are driving in. They are listed below in the order you reach them heading east from Seattle.

I-90 questions