Cutting across the central portion of the state, US 30 runs within close proximity of the Union Pacific Railroad's Overland Route for its entire length.

Small towns dot the entire route, which connects the larger cities of Denison, Ames, Marshalltown, Cedar Rapids, and Clinton.

[3] US 30 enters the western end of Iowa by crossing the Missouri River on the Blair Bridge, located east of the Nebraska town of the same name.

It enters the Boyer River valley through the Loess Hills, a region of wind-deposited silt extending from north of Sioux City to extreme northwestern Missouri.

[7] The rolling Loess Hills rise 50–100 feet (15–30 m) above the roadway while the land in the valley stays relatively flat.

The highway runs parallel to the Boyer River as well as the Overland Route in a general northeast direction from Logan.

Continuing east, the highway goes through the town of Glidden and passes to the north of Ralston, west of the Greene County line.

US 169 exits to the south at a partial cloverleaf interchange, while US 30 continues east through Boone County and descends into the Des Moines River valley.

From the interchanges to the Story County line one and three-quarters miles (2.8 km) away, Lincoln Way is designated as Iowa 930, but is never signed as such.

[11] East of the Dayton Avenue interchange is I-35, which connects US 30 to Minneapolis, Minnesota, to the north, and Des Moines to the south.

From Marshalltown, it travels five miles (8.0 km) to Le Grand, crossing over the Overland Route rail corridor on the west side.

[6] US 30 enters Benton County nine miles (14 km) north of Belle Plaine at an intersection with Iowa 21.

It continues east along a section line, passing the communities of Keystone, Van Horne, and Blairstown.

For four miles (6.4 km), US 30 / US 151 / US 218 is a wrong-way concurrency; that is, where two or more routes heading in opposite directions share the same highway.

East of I-380, US 30 / US 151 serve as a divider between the Lincolnway Village neighborhood to the south and a light industrial district to the north.

In Clinton County, it passes through Wheatland, Calamus, and Grand Mound before reaching a full cloverleaf interchange with US 61 at DeWitt.

US 30 overlaps US 61 for one mile (1.6 km), crossing the Union Pacific Overland Route in the process, and leaves US 61 via a trumpet interchange.

Five miles (8 km) east of DeWitt, it crosses back over to the north side of the Overland Route.

[3] As it approaches Mill Creek Parkway, it descends over 100 feet (30 m) in elevation into the flat Mississippi River valley, where it meets US 67.

[13] US 30 / US 67 head east along Lincoln Way and ascend 50 feet (15 m) onto a plateau, atop which reside stores and restaurants.

The first path connected as many downtown areas as possible, in order to create awareness about the Good Roads Movement and the Lincoln Highway.

It was 358 miles (576 km) of dirt roads, connecting Clinton, DeWitt, Cedar Rapids, Tama, Marshalltown, Ames, Jefferson, Denison, Logan, and Council Bluffs.

Between August 1918 and June 1919, Iowa's first seedling mile was built in Linn County, west of Mount Vernon.

[17] When counties could afford to build roads, the Iowa State Highway Commission required extensive grading to be performed before paving could occur.

In 1965, it was straightened and rerouted to the south of Ogden and Boone along an eleven-mile (18 km), four-lane stretch of road.

The bypass's proximity to the Union Pacific Railroad mainline resulted in an elevated roadway between Edgewood Road and Sixth Street SW.

When strong winds come from the south, fog produced by an Archer Daniels Midland plant adjacent to the highway billows over the road making driving dangerous.

The frequency of fog-related detours has decreased in recent years due to improved technology and the plant's expansion and relocation of cooling towers away from the highway.

In 2004, an $18.6-million (equivalent to $33.4 million in 2023 dollars[18]), four-lane section opened from east of Marshalltown to the Meskwaki Settlement west of Tama, bypassing Le Grand.

[44] While the Lincoln Highway has not been an official route for 99 years, it is still a source of pride in the communities and regions through which it passed.