New speed limit in Iowa takes effect July 1

DES MOINES, Iowa — While a new law increasing the speed limit on two-lane state highways goes into effect on Wednesday, officials are warning drivers that not all eligible roads will be changed when the law is enacted.

The new law passed this legislative session increases the default speed limit on two-lane state highways from 55 miles per hour to 60. The Iowa Department of Transportation will start updating speed limits on Wednesday, July 1, when the new law goes into effect.

The DOT is using aluminum overlays to alter the speed limit, which the department’s director of government and community relations, Daniel Yeh, says is cheaper than replacing the whole sign.

The DOT has to replace 1,794 signs along the state’s primary roadway system, and Yeh said he expects this to take at least one week.

There are around 3,465 more signs on county roads that county governments are responsible for changing, and that could take longer.

Despite the law increasing the default speed limit, Yeh said drivers are still required to drive the posted speed limits. Under Iowa Code, the DOT and counties are allowed to establish other speed limits based on engineering and traffic studies. Yeh said some roads aren’t safe enough for a five-mile increase, and will therefore stay the same even with the new law.

Yeh also said other changes could be coming to roadways with the higher speed limits to increase safety.

“For instance, we might need to adjust the passing zones on those roadways. We might need to adjust some of the safety features, like guard rails at curbs or some other markings painted on the roadway, just to guide about speed,” said Yeh.

The Legislative Services Agency, a nonpartisan group that develops fiscal information, determined that the new law will cost $825,000 over the next two years. Around $518,000 will be paid during fiscal year 2027, which starts July 1, and the remaining $307,000 will be paid in fiscal year 2028.

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