[2] The road clips the southeastern corner of Benton County, Iowa at Walford and it turns to the northeast toward Fairfax.

When it reaches the US 30 / US 218 freeway in Cedar Rapids, US 151 turns east onto the highway while US 151 Business continues northeast on Williams Boulevard SW.

[4] US 61/US 151 crosses the Mississippi River into Wisconsin via the Dubuque-Wisconsin Bridge from Dubuque, Iowa and passes through a cut in the river ridge before turning northward to the western terminus of WIS 11 after one mile (1.6 km) of due east travel.

WIS 35 and the Great River Road join the route at that interchange, heading north.

At Dickeyville, US 61, WIS 35 and the Great River Road route exit north off of US 151 into town.

[7] The section of expressway past Dodgeville follows the former Chicago and North Western Railroad, passing through rolling hills populated with farmland mixed with small woodlands.

Access to Ridgeway is by an interchange and a surface intersection with a short business route on CTH-HHH.

The freeway continues into Fitchburg and provides access to two interchanges at CTH-PD (McKee Road) and Williamsburg Way.

Verona Road passes through a residential and commercial area on the Southwest Side of Madison.

It crosses the same railroad corridor and passes Monona Bay to the west along South Park Street.

[7] At a cloverleaf interchange with I-39/I-90/I-94, a section of freeway begins and continues along US 151 northeast through commercial zones into residential areas.

A highway bypass was constructed north and west of Sun Prairie, but so much commercial and residential development subsequently happened to the north and west of the bypass that the route essentially divides Sun Prairie in half.

The route follows the edge of residential zones of the city before passing an industrial area at the northeastern end of the bypass.

Within this freeway section exists a level WSOR railroad crossing just after the CTH-E (East Burnett Street) underpass.

US 151 crosses at-grade intersections after the interchange with CTH-A northeast of Beaver Dam and encounters one more freeway section at Waupun, bypassing the city to the east.

The Waupun bypass also includes a level railroad crossing halfway between the CTH-M and WIS 26 interchanges.

The first study would preserve the Fond du Lac Bypass from I-41 to WIS 23, with the ultimate goal being freeway conversion.

[12] The multi-lane section of US 151 ends after turning north away from Fond du Lac and the route follows the east shore of Lake Winnebago for about half the length of the shoreline.

The previous route through Cedar Rapids was renamed US 151 Business (though the official state designation for it is Iowa 922).

US 151's northern terminus was changed in 2022 to end at I-43 instead of in downtown Manitowoc where WIS 42 traveled through before being rerouted onto I-43 in 1980.