Through the Des Moines area, the highway runs about one mile (1.6 km) north or south of the I-35/I-80 corridor.

US 6 is a cross-state route that connects Council Bluffs and Davenport by way of Des Moines and Iowa City.

[3] US 6 crosses the Missouri River via the Grenville Dodge Memorial Bridge, named after the Union Army general during the U.S. Civil War, into Council Bluffs with I-480.

Each year for Memorial Day, the rock is repainted with a patriotic scene by local artist Ray "Bubba" Sorenson II.

East of Adel, US 6 is a four-lane divided highway for 14 miles (23 km), during which it passes through Waukee, Clive, and Urbandale along Hickman Road and intersects I-35 / I-80.

Turning north, they run together for another mile (1.6 km) along Merle Hay Road, named after the first Iowa service member in World War I.

West of Altoona, it intersects US 65 and continues northeast passing the Adventureland theme park and Prairie Meadows casino.

After an interchange with Iowa 117, the highway is forced to the north to avoid crossing the river multiple times.

It turns off of Iowa 14 and enters the western side of Newton where it passes the Jasper County courthouse located in the downtown area.

[4] At Coralville, US 6 passes underneath I-80, but one-half mile (800 m) to the east, Coral Ridge Avenue provides direct access to I-80.

Near NorthPark Mall, it intersects Northwest Boulevard, which becomes Iowa 130 at I-80, and both one-way legs, Welcome Way southbound and Brady Street northbound, of US 61 Business, which, prior to 2010, was US 61.

[4] The two routes completely enter Bettendorf and descend into the Mississippi River valley, where they meet US 67 at a complex series of exit and entrance ramps.

[4] Before the U.S. Numbered Highway System came into being in 1926, roads in Iowa were maintained and promoted by local organizations which sought to drive traffic into their communities.

Two such organizations created virtually parallel routes connecting Council Bluffs and Davenport via Des Moines.

Interest in the original US 6 corridor has grown in the 21st century by people who seek to drive traffic back into their communities.

The route was built along the Chicago, Rock Island and Pacific Railroad between Council Bluffs and Des Moines.

The Great White Way passed through Oakland, Atlantic, Adair, De Soto, and Valley Junction.

In late 1912, the Great White Way was extended east to Davenport, passing through Pella, Oskaloosa, Washington, and Muscatine.

Their intention was to bring visitors to their towns by diverting some traffic from the nearby I-80 / US 6 corridor to the south and onto the historic road.

[18] The River-to-River Road (RRR) was also created in 1910 and also connected Council Bluffs and Davenport via Des Moines.

The route passed through Neola, Elk Horn, Guthrie Center, Adel, Des Moines, Newton, Marengo, Iowa City, and Wilton.

[15] The route's origins trace back to the 1909–1910 winter season which brought, on average, 11 inches (28 cm) of snow more than the previous year, which was followed by an unusually dry spring.

[19] Coupled with the advent of the Ford Model T, many Iowans complained about the lack of good roads in the state.

Further influencing the RRR corridor was an announcement from the American Automobile Association that the annual Glidden Tour would pass through Iowa.

Governor Carroll arranged for farmers who lived along the route to drag all 380 miles (610 km) of the road on the Saturday prior to the tour's arrival at precisely 9:00 am.

[24] Eight months later, the Iowa State Highway Commission reversed course and restored Primary Road Nos.

[24] On June 8, 1931, all of the Iowa portion of US 32 was absorbed into a newly extended US 6, which had previously connected Erie, Pennsylvania, and Cape Cod, Massachusetts.

The state highway commission recorded that, on average, over 1,900 vehicles used the road per day at any rural point.

[29] On April 29, 1947, the Iowa General Assembly approved an act designating US 6 as the Grand Army of the Republic Highway, a distinction the route shares in other states.

[30] Governor Robert D. Blue dedicated the Grand Army of the Republic Highway at the Iowa Old Capitol Building on September 28, 1947.