Missouri Speed Limit Now 75 MPH on Key Highways

Missouri Speed Limit Changes Affect Major Truck Routes

Commercial drivers will soon encounter higher speed limits on approximately 325 miles of Missouri interstate highways. The Missouri speed limit will rise from 70 to 75 mph on selected rural sections of I-29, I-35, I-49 and I-55. These highways carry freight between Missouri, Iowa, Arkansas and other regional markets.

The Missouri Department of Transportation announced the approved locations on October 21. However, the higher limit will not take effect everywhere at once.

MoDOT crews must install new signs before the change becomes enforceable. Truck drivers must continue following the currently posted limit until each sign is replaced.

Missouri Speed Limit Changes Cover Four Truck Routes

MoDOT selected eight interstate segments for the 75-mph limit.

I-29 in Northwestern Missouri

The higher limit will cover approximately 64 miles:

• Exit 56 in Andrew County to about 2.5 miles south of the Iowa border.

This section carries commercial traffic between the Kansas City area, St. Joseph and freight routes entering Iowa.

I-35 Toward the Iowa Border

Approximately 55 miles will increase to 75 mph:

• The northern Cameron city limit to about four miles south of the Iowa border.

I-35 is a major north-south route connecting Missouri with Iowa and markets farther north.

I-49 Near Arkansas

Two sections covering approximately 69 miles were approved:

• The Arkansas border to Exit 24.
• Exit 56 to just south of Exit 101 in Nevada.

The corridor serves freight moving between western Missouri, northwestern Arkansas and the central United States.

I-55 in Southeastern Missouri

Four sections covering approximately 137 miles will receive the higher limit:

• The Arkansas border to mile marker 16.6, south of I-155.
• Mile marker 19.8, north of Missouri Route 84, to mile marker 64.9 at the Route AA bridge.
• Mile marker 70.5, north of Route HH, to mile marker 86.6, south of Route PP.
• Mile marker 106.4, north of Exit 105, to mile marker 164.9 at the Jefferson County line.

I-55 is an important freight corridor connecting Missouri with Arkansas, Tennessee and Mississippi River markets.

Drivers Must Follow the Posted Signs

MoDOT plans to begin changing signs during the fall. The agency did not announce one effective date covering every approved section.

The new limit applies only after a 75-mph sign is installed.

A corridor may therefore contain both 70- and 75-mph sections while crews complete the work. This will be particularly important on I-55, where the approved portions are separated by sections that were not included.

Commercial drivers should rely on posted signs rather than assuming the entire interstate has changed.

The announcement does not increase speed limits on every rural interstate in Missouri. Only the locations selected after MoDOT’s review are affected.

Governed Trucks Could Face Larger Speed Differences

Many commercial trucks are governed below 75 mph. Carriers may also establish maximum operating speeds that are lower than the legal limit.

The new limit does not change those vehicle settings or company policies.

As passenger vehicles begin traveling at the higher limit, governed trucks may experience a larger difference between their speed and surrounding traffic. That difference could become noticeable on grades, during passing maneuvers and near entrance ramps.

The speed limit is also a maximum rather than a required operating speed. Drivers remain responsible for adjusting their speed for traffic, weather, visibility and roadway conditions.

Why MoDOT Selected These Highway Sections

A new Missouri law permits MoDOT to increase the maximum speed on eligible rural highways to 75 mph.

The law did not automatically raise the limit across the state. MoDOT evaluated each eligible location before deciding where to install higher limits.

The review considered:

• Commercial truck volumes.
• Total traffic volumes.
• Current vehicle speeds.
• Crash history.
• Terrain and road design.
• Existing safety features.
• Active construction.
• Speed limits in bordering states.

Truck volumes were therefore one of the factors used to select the approved corridors.

MoDOT also published an online map showing the approximate locations of the affected segments.

Enforcement Will Depend on the Posted Limit

Drivers can expect the existing speed limit to remain enforceable until signs change.

This means one section may still be limited to 70 mph even if a nearby section has moved to 75 mph. The transition could create more frequent changes in the posted limit along some routes.

The Missouri State Highway Patrol emphasized that drivers must reduce their speed when conditions make the maximum posted speed unsafe.

Higher limits do not change other commercial-vehicle requirements. Hours-of-service rules, vehicle inspections, weight limits and carrier safety policies remain in effect.

MoDOT Could Return Sections to 70 MPH

MoDOT said it will monitor crash data after the new limits take effect.

The department may return a highway segment to 70 mph if future results indicate that a lower limit is necessary.

That review makes the change adjustable rather than permanent under every condition.

What Truck Drivers Should Expect

Commercial drivers traveling through Missouri should prepare for a gradual transition instead of one statewide change.

The main points are:

• Approximately 325 miles were approved for 75-mph limits.
• The changes affect selected sections of I-29, I-35, I-49 and I-55.
• Existing limits remain in place until new signs are installed.
• Some corridors will contain alternating 70- and 75-mph sections.
• Carrier policies and governed-truck settings do not change.
• MoDOT will continue evaluating crash data after implementation.

The new Missouri speed limit could allow faster travel on some rural freight corridors. It will also require close attention to posted signs and changing traffic speeds.