Through southwestern Iowa, the highway is, for the most part, a two-lane rural road with at-grade intersections; there are interchanges with US 59 near Emerson and US 71 near Stanton and Villisca.

Highways when the system was created in 1926, though it was preceded by the Blue Grass Route, a 310-mile-long (500 km) auto trail that connected Council Bluffs and Burlington.

In 1920, the Iowa State Highway Commission (ISHC) assigned route numbers to roads in order to improve wayfinding for travelers.

Their subsequent lab analysis and delayed reburial created a controversy that eventually led to the Native American Graves Protection and Repatriation Act.

Continuing east, US 34 briefly curves to the north and passes over the BNSF Railway line that carries the California Zephyr.

[6] East of Thayer, it passes Murray and then turns to the southeast in order to enter the sprawling commercial area on the western edge of Osceola.

It curves to the southeast along the bank of the Des Moines River and intersects Wapello Street, which carries both US 63 Business and Iowa 149.

Between those towns, an interchange with Iowa 16 directs traffic to Eldon and the house that served as the backdrop to Grant Wood's painting American Gothic.

As it approaches Middletown, home of the Iowa Army Ammunition Plant, the highway takes a 90-degree turn to the east and becomes a freeway.

[19] In the mid-1990s, the Iowa Department of Transportation began an ambitious project to expand seven important corridors, one of which connected Des Moines to Burlington.

Charles H. Thomas of Kent suggested the road's name because it traversed through, as he saw it, "the finest blue grass region of the country".

Long organized the first committee meeting of residents along the route who were interested in promoting their highway and in good roads in general.

[8] In 1913, shortly after the Iowa General Assembly passed legislation allowing road associations to officially register their route with the Iowa State Highway Commission, the Blue Grass Road Association sent the highway commission a check for $5 (equivalent to $164 in 2023[25]) with the intent of becoming the first route registered by the state.

[26] In 1919, the Iowa General Assembly passed a bill that created a fund for improving and hard-surfacing nearly 6,300 miles (10,100 km) of primary roads in the state.

[10] Originally, US 34's national western end was the corner of Main Street and Broadway in Council Bluffs, the same as Primary Road No.

[30] US 275, which was designated in the latter half of 1931 as a shorter route between Omaha, Nebraska, and St. Joseph, Missouri,[31] joined US 34 near Glenwood and ended in downtown Council Bluffs.

In 1935, AASHO consented and the highway was rerouted west at Glenwood to cross the Missouri River at Plattsmouth and end at Grand Island, Nebraska.

A celebration marking the occasion was held at the Iowana Hotel in Creston attended by over 5,000 guests, including Governor John Hammill.

US 63 was relocated at the same time; it was rerouted to the eastern side of the John Deere plant along the bank of the river and met up with the new US 34 road.

[39] A new bridge over the Des Moines River, near the John Deere plant, along with an eastern bypass of the downtown area opened to traffic in 1966.

[41] As early as 1958, an 11-member road study committee recommended the construction of a state freeway system not to exceed 2,000 miles (3,200 km) in length.

Work was scheduled to begin in 1976 after the freeway opened up to Roosevelt Avenue, but financial problems at the Iowa Highway Commission, including a 42-percent increase in construction costs, led to delays.

They also asked that the plans to widen US 61 from West to Sunnyside Avenues in western Burlington, which included the connection between the 534 freeway and US 34, be scrapped entirely.

[55] In 1971, during the grading phase of the project, highway workers found about twenty gravesites along with the skeleton of a Native American teenage girl.

A district court judge ordered the highway commission to pay for the costs of moving the remains to the cemetery in Glenwood, while the native skeleton was taken to the state archaeology lab in Iowa City for analysis.

[16] Budget constraints in the early part of the 2000s caused the Iowa DOT to table some highway projects, but they were still committed to completing the six high-priority corridors.

Governor Chet Culver presided over the ribbon cutting ceremony that celebrated the opening of the Fairfield bypass and the completion of the 1996 highway plan.

[73] Starting in 1974, tollbooth attendants weighed tractor-trailers on either side as the bridge only allowed trucks to cross safely from one direction at a time.

[76] Beginning in the 1990s, the Iowa DOT and Nebraska Department of Roads (NDOR) began looking at ways to improve access to I-29 from the southern parts of the Omaha metropolitan area.

Governors Terry Branstad of Iowa and Dave Heineman of Nebraska, both of whom spoke at the opening ceremony, felt the bridge would be a boon to the local economy and attract jobs.