Wyoming In
Wyoming, US 18 runs concurrent with
US 20 from
I-25 to
Lusk, where US 18 branches off to run concurrently with
US 85. At the unincorporated community of
Mule Creek Junction in northeastern
Niobrara County, US 18 leaves US 85. This stretch from US 85 to the South Dakota border is the only segment of US 18 in Wyoming which is not cosigned with another highway. Running for nearly , US 18 has a speed limit of with the exception of its ending terminus at Orin and the portion throughout Lusk.
South Dakota US 18 enters
South Dakota west of
Edgemont. It passes through
Hot Springs, the
Pine Ridge Indian Reservation, the
Rosebud Indian Reservation,
Winner, and
Gregory before crossing the
Missouri River near
Pickstown over
Fort Randall Dam. East of the Missouri River, US 18 passes through (or near)
Lake Andes and
Tripp before a brief concurrency with
I-29 near
Worthing. East of I-29, US 18 passes through
Canton before crossing the
Big Sioux River into Iowa. The Oyate Trail is one of the names given (in the late 1990s) to the section of US 18 traveling across South Dakota from I-29 east of
Vermillion to
Maverick Junction. Named in an attempt to encourage more tourism traffic through the lands of various
Indigenous peoples in southern South Dakota, it passes through or near the
Yankton Sioux, Rosebud, and Pine Ridge Indian reservations, crossing the James River Valley, the Missouri River near Fort Randall Dam, portions of Pine Ridge, and the
High Plains of South Dakota, connecting the urban areas of the middle Missouri River with the
Black Hills. Portions of the road were known as the Grant Highway, Black Hills Sioux Trail, and part of the Omaha, Rosebud and Black Hills Highway, as well as the Custer Battlefield Trail. Towns along the road include Gregory, Winner,
Olivet,
Mission,
Martin,
Batesland, and
Pine Ridge. Nearby towns and locales of interest include
Rosebud (capital of the Rosebud Sioux Tribe) and
Wounded Knee. The South Dakota section of US 18, other than the concurrency with I-29, is defined at South Dakota Codified Laws § 31-4-141.
Iowa US 18 enters
Iowa via a Big Sioux River crossing northeast of
Beloit. It overlaps
US 75 for near
Hull and
US 59 for near
Sanborn. It then overlaps
US 71 through
Spencer. US 18 passes through
Emmetsburg before intersecting
US 169 at
Algona. US 18 then continues east through
Garner before intersecting
I-35 in
Clear Lake. After a brief concurrency with I-35, US 18 continues as a
freeway, bypassing
Mason City to the south. At
Charles City, US 18 becomes a rural two-lane highway again, except for a brief concurrency with the
US 63 bypass of
New Hampton. After passing through
West Union, it turns northeast and joins
US 52 at
Postville, then leaving US 52 about east of
Monona before crossing the
Mississippi River into Wisconsin via the
Marquette–Joliet Bridge in the city of
Marquette. US 18 is the designated route of the
Avenue of the Saints between Clear Lake and Charles City.
Wisconsin Upon entry into
Wisconsin at
Prairie du Chien, US 18 is the terminus for
State Trunk Highway 60 (WIS 60). The two routes are then concurrent until
Bridgeport where WIS 60 splits off to the east and US 18 crosses the
Wisconsin River and turns east on the other side. The route joins the
US 151 expressway in
Dodgeville and the two remain concurrent east to
Madison. US 18 follows
US 12 south of Madison and passes through or around
Cambridge,
Jefferson, and
Waukesha before terminating in Milwaukee at the junction of East Michigan Street and Lincoln Memorial Drive in downtown. ==Major intersections==