Iowa Road Network

By | October 13, 2022

Like many states on the Great Plains, Iowa has a very dense road network divided into a grid. This grid divides the agricultural areas and many of these roads are paved, so that Iowa has an extensive network of paved roads.

Road management

The state highway authority is the Iowa Department of Transportation, abbreviated IowaDOT. The IowaDOT manages 14,273 miles of road, a relatively small portion of Iowa’s total road network, which covers 184,208 miles. Most of it is in the management of the counties. IowaDOT also operates 4,103 of the 24,661 bridges in the state. Iowa has relatively many medium-sized bridges, mainly over the Mississippi River and Missouri River. In 2017, Iowa had the highest number of degraded bridges in the United States, but road conditions improved the most in 2017 of any state.

The IowaDOT has its origins in the Iowa State Highway Commission, which was established in 1904. Iowa was one of the first states west of the Mississippi River to have a state highway commission. Iowa was also one of the longest-serving states with such a name, with other states having a highway department, Iowa retained the State Highway Commission until 1974, when it was renamed the Iowa Department of Transportation. During that period, most states switched to a ‘Department of Transportation’.

It is striking that the IowaDOT is not headquartered in the capital Des Moines, but in the city of Ames. This is because it has its origins in Iowa State University (then: Iowa State College).

  • Bittranslators: State overview of Iowa, including geography, economy, population and history as well as introduction to major cities of Iowa.

Interstate Highways

Several Interstate Highways run through Iowa. Interstate 29 forms a north-south route along the state’s western border, through Council Bluffs to Sioux City. I-29 follows the Missouri River here. Interstate 35 runs north-south through the center of the state, via the state capital Des Moines. Interstate 74 begins in Davenport and soon crosses the Mississippi River, which forms the border with Illinois. Interstate 80 is Iowa ‘s primary east-west route, running from Council Bluffs through Des Moines to Davenport. This is one of the major east-west routes in the United States. Along I-80 west of Davenport is the ‘Iowa 80’, the largest truck stop of the United States.

In addition, there are some auxiliary routes of the Interstate Highways in Iowa. Interstate 129 forms the southern bypass of Sioux City and is located partly in Nebraska. Interstate 235 opens up downtown Des Moines and, together with I-35/I-80, forms a ‘box’ of freeways through the city. Interstate 280 forms an alternate route around Davenport and forms the western edge of the Quad Cities on the Illinois border. Interstate 380 connects Waterloo to Iowa City, via Cedar Rapids. This is Iowa’s main regional Interstate Highway. Interstate 480 runs just one mile into Iowa and is part of the route through Omaha, Nebraska. The Interstate 680 also runs part of Nebraska and is part of an alternate route around Omaha. However, I-680 travels a significantly greater distance in Iowa than I-480.

  • Deluxesurveillance: Nickname of Iowa as The Hawkeye State. Also covers geography, history, economy, politics and administration of the state.

US Highways

Numerous U.S. Highways crisscross Iowa, but few are as important as US 20, which forms an east-west route through the northern half of the state, from Sioux City via Fort Dodge and Waterloo to Dubuque, and is largely converted into a freeway, and elsewhere as 2×2 divided highway. Other major US Highways equipped with 2×2 lanes are US 18 from Clear Lake to Charles City, US 34 in the southeast of the state, US 61 from Davenport to Dubuque, US 63 from Waterloo to New Hampton, US 75 from Sioux City to Le Mars, the US 151 between Cedar Rapids and Dubuque and US 218 from Keokuk via Iowa City, Cedar Rapids and Waterloo to Charles City. US 218 partly coincides with I-380.

State Highways

Iowa’s secondary road network is made up of the state highways, which are divided into primary roads and secondary roads, which are also known as farm to market roads. The secondary roads are actually not state highways, but county highways. The primary roads are the actual state highways and are numbered from 1 to 999. In 2003 a significant part of the state highways was transferred to the counties, so that the state only manages the core network of roads. A large part of the numbers above 200 has been dropped. Road numbering for state highways was introduced in 1920.

There are hardly any state highways that have been developed as freeways, the only freeways worth mentioning are Iowa 5 as a Des Moines ring road and part of Iowa 100 in Cedar Rapids. Portions of Iowa 60 and Iowa 163 have short grade-separated bypasses, but are single-storey between villages.

Toll roads

There are no general toll roads in Iowa, nor have there ever been. However, a small number of bridges over the Mississippi River and Missouri River have to pay tolls.

The toll bridges in Iowa;

  • Bellevue Bridge (Missouri River)
  • Fort Madison Bridge (Mississippi River)
  • Plattsmouth Bridge (Missouri River)

These bridges are outside the main road network, there are no electronic payment options.


Before the Interstate Highway system was created in 1956, Iowa didn’t have a mile of highway. The state had already completed the rapid growth of the population around 1910, after which the growth slowed down, sometimes even stagnating or decreasing. Iowa has historically been a fairly important state for through traffic. This was because east-west traffic in Iowa had to cross two major rivers; the Mississippi River on the Illinois border and the Missouri River on the Nebraska border. The major through routes before the highway era were US 6 from Omaha via Des Moines and Iowa City to Bettendorf, US 34 further south via Burlington, US 20 in the north of the state, all as east-west routes. For north-south traffic, US 65 and US 69 were important through the center of the state, and US 61 to the east. To the west there was no major north-south connection, traffic then used US 75 and US 77 in Nebraska, just over the Missouri River. This was because Omaha was the largest city in this area, and was located west of the river.

After the Interstate Highway system was created, construction of the highway network in Iowa got off to a fast start, similar to its southern neighbor Missouri. The very first freeway was I-35 in Des Moines, which opened on September 21, 1958. Just a few days later, the second highway, I-29, opened in Sioux City on October 1, 1958. In the early 1960s, two axes were rapidly built, I-80 from Des Moines to Davenport and I-29 from Council Bluffs to Sioux City. Other parts were also opened up, but were not completed until the late 1960s or early 1970s. In 1972, I-29 and I-80 were passable through Iowa. In 1975, I-35 was open to traffic, completing the main route network in 17 years. Also, during the 1960s, Iowa’s first urban highway was constructed, I-235 through Des Moines.

Several more shorter highways were completed in the 1970s. In 1973, I-280 was completed along the west side of Davenport, and in 1974 I-74 was completed through Bettendorf slightly to the east. I-129 was completed as a bypass of Sioux City in 1976, and I-680 was completed in 1979. Most bridges over the major rivers also became toll-free during this time, previously almost all bridges over the Mississippi and Missouri were toll bridges. The bridges in Interstate Highways have never been toll bridges. The last major new construction project in the state of Iowa was the construction of I-380 from Iowa City through Cedar Rapids to Waterloo. The section between Iowa City and Cedar Rapids was completed in 1976, but it was not until 1985 before the section between Cedar Rapids and Waterloo was opened.

No new long-distance highways have been built since the 1980s. However, some US Highways have been made partly grade separated, such as US 18 and US 20, which have grade separated intersections over longer distances, and fragments of other roads. Between 1996 and 2002, the second Des Moines bypass was opened, along the south and east sides of the city. However, this is not an Interstate Highway, but is numbered SR-5 and US 65. Iowa’s population has grown only slightly since 1950, from about 2.6 million in 1950 to just over 3 million in 2010. however, the state has already acted to prevent a decline, which was not so obvious in the 1980s. In 2018, the doubling of the entire 490 kilometers of the US was 20 to a 2×2 divided highway in the north of the state.

Iowa Road Network