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Speed limits

MDOT Statewide Sign crew changing the speed limit sign on US-127 to 75 mph.

Speed limits

MDOT and the Michigan State Police (MSP) jointly set speed limits on state trunkline highways (I, M, and US routes) based on Section 257.627 Section 257.627 and Section 257.628 of the Michigan Vehicle Code. Speed limits are either statutory or modified.

A speed limit sign along a Michigan freeway indicating 70 mph for cars and 60 mph for trucks.

Statutory speed limits

Statutory speed limits are set by law and applied statewide. Examples include:

  • 25 mph within a residential subdivision.
  • 55 mph on trunkline and county highways without a specific speed limit.
  • 70 mph on limited access freeways without a specific speed limit.

Statutory speed limits can be changed by modified speed limits.

MDOT crews update signs to 75 mph in Clinton County.

Modified speed limits

Modified speed limits are set by agencies with legal authority and jurisdiction over the highway. For example, MDOT and MSP share authority over state trunkline highways, even when these routes pass through local municipalities.

These speed limits can be established or reviewed due to:

  • Changes in road design,
  • Land use,
  • Crash patterns,
  • Compliance issues, or
  • Requests from citizens or local municipalities.

Section 257.628 of the Michigan Vehicle Code requires modified speed limits to be set based on traffic engineering practices and an objective analysis of the highway's characteristics, as well as the speed at or below the 85th percentile of the speed drivers travel.

85th percentile speed and highway characteristics

The 85th percentile speed is the speed at or below which 85 percent of traffic moves. State law allows setting speed limits below this percentile if an engineering and safety study shows a hazard to public safety not reflected by the 85th percentile speed; however, the law does not allow the speed limit to be set below the 50th percentile speed (speed at or below 50 percent of traffic moves).

When setting a modified speed limit, highway characteristics considered include:

  • Roadway environment (roadside development, driveways/access points, land use), road type, public transit, parking, and pedestrian and bicycle facilities/activity.
  • Roadway characteristics (lane width, shoulder condition, alignment, medians and sight distance).
  • Geographic context (urban versus rural).
  • Crash history (last three to five years).

2017 speed limit increases

Public Act 445, signed into law in 2016, required MDOT and MSP to increase speed limits by the end of 2017:

  •          75 mph on at least 600 miles of limited access freeway.
  •          65 mph on at least 900 miles of trunk line highways.

Freeway route speed limit increases to 75 mph

The speed limit has been increased on 614 miles of freeway in Michigan.

Route Starting point Ending point Miles Counties
I-69 I-69 Business Route (Saginaw Highway) Swartz Creek 33 Clinton, Genesee and Shiawassee
I-69 Genesee/Lapeer county line I-94 51 Genesee, Lapeer and St. Clair
I-75 Bay City Mackinaw City 175 Arenac, Bay, Cheboygan, Crawford, Emmet, Ogemaw, Otsego and Roscommon
I-75 St. Ignace Sault Ste. Marie 50 Chippewa and Mackinac
US-10 M-115 I-75 57 Bay, Clare, Isabella and Midland
US-31 South Oceana County line US-10 37 Mason and Oceana
US-127 I-69 St. Johns 18 Clinton
US-127 Ithaca I-75 98 Clare, Crawford, Gratiot, Isabella and Roscommon
US-131 M-57 North of Manton 95 Kent, Montcalm, Mecosta, Osceola and Wexford

Non-freeway route speed limit increases to 65 mph

The speed limit has been increased on 943 miles of non-freeway routes in Michigan.


Route Starting point Ending point Miles Counties
US-2 Rapid River St. Ignace 119 Delta, Mackinac and Schoolcraft
US-2 Wakefield Iron River 67 Gogebic and Iron
US-23 Cheboygan East of M-65 52 Cheboygan and Presque Isle
US-45 North of US-2 M-26 33 Gogebic and Ontonagon
M-28 East of Harvey Christmas 33 Alger and Marquette
M-28 Munising I-75 109 Alger, Chippewa, Luce and Schoolcraft
M-28 Wakefield US-41 75 Baraga, Gogebic, Houghton and Ontonagon
M-32 Atlanta Alpena 36 Alpena and Montmorency
M-33 Atlanta Onaway 25 Montmorency and Presque Isle
M-37 US-10 north junction Mesick 35 Lake and Wexford
M-55 US-31 Cadillac west 43 Manistee and Wexford
M-64 M-28 Old M-107 18 Ontonagon
M-65 US-23 M-32 west junction 78 Alcona, Alpena, Arenac and Iosco
M-65 M-32 east junction US-23 18 Alpena and Presque Isle
M-68 I-75 US-23 40 Cheboygan and Presque Isle
M-72 Grayling Mio 29 Crawford and Oscoda
M-72 Fairview M-65 north junction 12 Alcona and Oscoda
M-72 M-65 south junction Harrisville 22 Alcona
M-77 US-2 M-28 16 Schoolcraft
M-115 Mesick Benzonia 23 Benzie and Wexford
M-123 I-75 Paradise 53 Chippewa and Mackinac
M-231 M-45 M-104 7 Ottawa