Oregon US 20 begins at an intersection with
US 101 in
Newport, Oregon, and runs generally eastward towards
Idaho. On the way it goes over the
Central Oregon Coast Range, through several
Willamette Valley cities including
Corvallis and
Albany, climbs the
Cascade Mountains over
Santiam Pass, goes through
Bend, and traverses the
Oregon High Desert after passing through
Burns. It eventually overlaps
US 26 in
Vale, and the two highways continue concurrently to the
Idaho border.
Idaho US 20 crosses into Idaho from Oregon northwest of
Parma. It
runs concurrently with
US 26 and joins
US 95 through Parma. US 20/US 26 leaves US 95 southeast of Parma and runs to
Caldwell where US 20/US 26 joins with
I-84 and
US 30 for a short time. These four highways parallel each other (on two roadways) to
Boise where US 20/US 26 runs through downtown before joining with I-84 and US 30 again to
Mountain Home, where it departs at exit 95 to head east, past
Rattlesnake Station,
Anderson Ranch Dam road, and cresting at Cat Creek summit at
above mean sea level. It continues into and across
Camas County through
Fairfield to Timmerman Junction, the intersection in
Blaine County with
State Highway 75, the route to
Sun Valley,
Galena Summit, and
Stanley. US 20 continues east through
Picabo and
Carey, joined with US 26 and
US 93, to
Craters of the Moon and
Arco, where US 93 splits off and turns north-northwest to climb the
Big Lost River valley. US 20/US 26 continues on through the
Idaho National Laboratory, where the highways split just west of
Atomic City; US 26 heads to
Blackfoot and US 20 to
Idaho Falls, where it turns north-northeast to pass near
Rexburg as a freeway. US 20 then climbs through the communities of
St. Anthony,
Ashton, and
Island Park, and crosses the
Continental Divide at
Targhee Pass at , entering
Montana west of
West Yellowstone.
Montana In the state of Montana, US 20 runs for less than . It runs from the Idaho state line to
West Yellowstone, Montana, the western entrance to
Yellowstone National Park. US 20 is known as the
Targhee Pass Highway in Montana. While US 20 and other U.S. Routes are officially discontinuous through the park, some commercially produced maps show these highways running inside Yellowstone National Park itself along its unnumbered roads and across the Montana–Wyoming state line.
Wyoming In the state of Wyoming, the eastern segment of US 20 starts at the eastern entrance to
Yellowstone National Park along with the western termini of
US 14 and
US 16. These three routes run east to
Greybull, where US 14 continues east and US 16/US 20 turns south; at
Worland, US 16 turns east while US 20 continues south, passing through
Wind River Canyon south of
Thermopolis. US 20 joins US 26 in
Shoshoni, where it turns east, and they continue all the way through
Casper. From Casper, the two highways parallel
I-25 and
US 87 for 26 miles, until all four link up together just southeast of
Glenrock. These four routes stay combined to
Orin, where US 20 turns east from I-25, at the western end of
US 18. US 18 and US 20 are concurrent from Orin to
Lusk, where US 18 turns north and US 20 continues east into Nebraska.
Nebraska Within
Nebraska, US 20 is a
state highway that begins on the
Wyoming–Nebraska state line west of
Harrison near the
Niobrara River and runs to the Nebraska–
Iowa state line in
South Sioux City. Throughout its length the route passes through a diverse range of landscapes including
bluffs and
escarpments in the Northwest
Panhandle, the
Nebraska Sandhills in the northern part of the state, and rolling hills and plains through Randolph, Nebraska as the highway approaches the
Missouri River valley south of
Sioux City, Iowa. Throughout its length, US 20 is a two-lane highway with the exception of the easternmost which is four-lane divided highway, the last of which is concurrent with
Interstate 129.
Iowa US 20 enters Iowa at
Sioux City via the
Missouri River crossing with
I-129 and
US 75. After skirting the southeast side of Sioux City as a freeway with US 75, US 20 continues east as an
expressway to
Moville. From Moville through north of Early at the junction with U.S. Route 71 and
Iowa Highway 471, US 20 was reconstructed from a rural two-lane highway to a four-lane road. This segment re-opened October 19, 2018 and made it so that US 20 is a continuous four-lane highway for its entire length in Iowa. It passes to the north of
Sac City, where it has another interchange with the realigned
U.S. Route 71, then passes to the south of
Fort Dodge and
Webster City before intersecting
I-35 near
Williams. A new segment of freeway between
US 65 south of
Iowa Falls and
Iowa Highway 14 opened in 2003 creating a continuous four-lane route from Moorland to Dubuque. The new segment shaved off US 20's length in Iowa. In the
Waterloo/
Cedar Falls area, the segment of US 20 overlapped by the
Avenue of the Saints, which is also designated as Iowa Highway 27. US 20 passes
Independence,
Manchester, and
Dyersville before reaching
Dubuque. At Dubuque, US 20 crosses into Illinois over the
Julien Dubuque Bridge.
Illinois In the state of Illinois, US 20 begins in
East Dubuque, following southeastward along the Mississippi River, and continues into the very hilly
Driftless Area of northwest Illinois through
Galena and
Elizabeth. The highway then transitions eastward from the Driftless Area to the Interior Plains near
Stockton. The road continues as a bypass north of
Freeport, and then runs as a freeway along the southern fringe of
Rockford. From Rockford to
Chicago, Illinois, US 20 is a mixture of four-lane expressway, four-lane limited access freeway, and winding two-lane surface road. It is signed as "General U.S. Grant Highway" after
Ulysses S. Grant. U.S. 20 runs through the south side of Chicago as 95th Street. US 20 exits Illinois along with
US 12 and
US 41 as Indianapolis Boulevard south of the
Chicago Skyway.
Indiana In the state of Indiana, US 20 enters from the west beneath the
Chicago Skyway with US 12 and US 41. US 20 passes through heavily industrialized northwestern Indiana and is the main east–west artery through
Gary. It then parallels US 12 to just west of
Michigan City before running due east through
New Carlisle to
South Bend. US 20 travels around South Bend and
Elkhart on the
St. Joseph Valley Parkway, a four-lane limited access freeway, then returns to surface road east of Elkhart. US 20 then passes through
LaGrange and
Angola, intersecting with
I-69 before leaving Indiana just north of the eastern terminus of the
Indiana Toll Road. From
Gary to
South Bend, US 20 was built as the Dunes Relief Road. During the 1930s and 1940s the Dunes Highway,
US 12, was becoming more crowded as housing lots and communities developed in the Indiana Dunes. Today, there are numerous communities along US 20 and the lakefront, including Gary,
Portage,
Burns Harbor,
Porter,
Chesterton,
Pines, and
Michigan City. Most notably, the route is one of the main access roads to
Indiana Dunes National Park.
Ohio US 20 enters
Ohio from Indiana just west of
Columbia and traverses east through
Pioneer and
Alvordton to
Fayette. It continues east through
Oakshade,
Assumption and becomes five-lane, non-limited access roadway into
Sylvania to
Toledo, and then turns south until into the Toledo suburb of
Maumee. After Maumee, US 20 crosses Maumee River curving back east becoming 2 lanes through
Perrysburg to
Woodville, where it becomes a four-lane, non-limited access highway. It bypasses
Fremont while concurrent with
US 6,
State Route 53, and
State Route 19, and then travels through the northern edge of
Clyde and the downtown area of
Bellevue, where it is joined by
State Route 18. From there the four-lane highway continues through
Monroeville and bypasses
Norwalk, then becomes a two-lane highway from there to
Oberlin. Continuing east, US 20 traverses through
Elyria,
North Ridgeville,
Westlake,
Rocky River,
Lakewood and
Cleveland, where it goes right through
Public Square. East of Cleveland US 20 follows the southern shore of
Lake Erie, following
Euclid Avenue from Public Square, and traverses
Euclid,
Wickliffe, where it intersects with I-90,
Mentor,
Painesville,
Madison,
Geneva,
Ashtabula and crosses into
Pennsylvania at
Conneaut.
Pennsylvania US 20 runs for nearly across
Erie County, Pennsylvania, most of that time just south of the
CSX/
Amtrak railroad tracks. US 20 appears as West Ridge Road eastward from the Ohio border through
Springfield,
Girard,
Fairview and
Millcreek townships. At the intersection with
Pennsylvania Route 832, just outside the
Erie city limits, it becomes West 26th Street. After it reaches city center at the intersection with State Street, it becomes East 26th Street. It turns sharply northward as Broad Street at the
Bayfront Connector, then turns east again as Buffalo Road through
Wesleyville and
Harborcreek Township. Buffalo Road turns sharply northward at the town of Harborcreek. US 20 intersects with Pennsylvania Route 955 and resumes its eastward journey. At
North East Township, US 20 becomes West Main Road. Within the town limits, it becomes West Main Street until it reaches the town center at its intersection with Pennsylvania Route 89, where it becomes East Main Street. Outside the town limits it becomes East Main Road until it reaches Pennsylvania's border with
New York.
New York In
New York, US 20 runs roughly parallel to the
New York State Thruway (I-90) throughout the state. The route runs concurrently with
New York State Route 5 twice, with the second overlap extending across
Western and
Central New York from
Avon to
Auburn running along the top of the
Finger Lakes crossing
Canandaigua and
Seneca Falls along the way. US 20 runs across the rural
Cherry Valley Turnpike between
Skaneateles and
Albany. US 20 was also known as the Boston-Buffalo highway prior to the construction of the New York Thruway and Massachusetts Turnpike.
Massachusetts at
Kenmore Square, near the
Boston Citgo sign In Massachusetts, US 20 runs roughly parallel to I-90
Mass Pike, intersecting it directly at exit 10 and indirectly at exit 94. In part of
Berkshire County, US 20 runs north–south as it runs concurrently with
US 7. It is known as the "Jacob's Ladder Trail" as it crosses the
Berkshire Hills between
Lee in Berkshire County and
Chester in
Hampden County. From Chester to
Westfield, US 20 and the
Boston and Albany Railroad follow the
Westfield River down to the broad valley of the
Connecticut River. In
Springfield, US 20 runs concurrently with
I-291 between Plainfield Street and Page Boulevard; it follows Boston Road as it leaves Springfield and travels through the town of
Wilbraham, eventually becoming Main Street in
Palmer. In
Shrewsbury, US 20 is called "Hartford Turnpike". In
Northborough, and
Worcester it is called "Southwest Cutoff", until it merges with the original
Boston Post Road in Northborough (Southwest Cutoff and West Main Street). Southwest Cutoff was created at the turn of the century to bypass truck traffic around Shrewsbury center as well as connecting to the
Boston and Worcester Turnpike. In parts of eastern Massachusetts, US 20 follows the route of the old
Boston Post Road and passes by
Longfellow's Wayside Inn, in
Sudbury, the oldest continually operated Inn in America. In 1926, after engineers determined that heavy truck traffic on the Boston Post Road was damaging the foundations of the Inn,
Henry Ford, then owner and proprietor, ordered the construction of the mile-and-a-half-long Route 20 bypass. Upon its completion on December 11, 1928, he sold it to the Commonwealth of Massachusetts for $1 and never cashed the check. According to the
Boston Herald the by-pass cost Ford $288,000, equivalent to roughly $4.7 million in 2021. The original route of US 20 is now called Wayside Inn Road. US 20 continues from Sudbury through
Wayland,
Weston,
Waltham,
Watertown and then into
Boston through
Allston and
Fenway–Kenmore. U.S. Route 20's official eastern terminus is in
Kenmore Square at the intersection of
Commonwealth Avenue,
Beacon Street, and
Brookline Avenue, where the alignment becomes
Massachusetts Route 2. Route 2 continues for a short distance where it terminates at
Massachusetts Route 28. ==History==