(Speed limit in miles per hour)
|State||Interstate||Other limited-access roads1||Other roads|
|Arizona||75||65||65||65, Trucks: 65|
|Arkansas||70; Trucks: 65||55||602||55|
|California||70; Trucks: 55||65, Trucks: 55||70, Trucks: 55||65, Trucks: 55|
|District of Columbia||n/a||55||n/a||25|
|Idaho||75; Trucks: 65||75||65||65|
|Illinois||65||55||65, Trucks: 55||55|
|Indiana||70; Trucks: 65||55||60||55|
|Kentucky||65; 70 on specified segments of road4||65||65||55|
|Michigan||70 (trucks 60); <70 (trucks 55)||65||70||55|
|Montana||75; Trucks: 65||65||Day: 70; Night: 65||Day: 70; Night: 65|
|Oregon||65; Trucks: 55||55||55||55|
|Washington||70, Trucks: 60||60||60||60|
1 Limited-access roads are multilaned roads with restricted access using exit and entrance ramps rather than intersections.
2 Upon completion of a study, due to be completed on or before 09/15/08, the speed limit on any 2-lane highway or 4-lane highway shall be increased to 65 miles per hour if the findings of the study support the increase on a particular 2-lane highway or 4-lane highway.
3 The maximum speed limit is established by county ordinance or by the director of transportation.
4 The speed limit may be increased to 70 mph on specific segments of highway upon the basis of an engineering and traffic investigation. On 07/10/07, highway officials increased the speed from 65 mph to 70 mph on Interstate 75 south of US 42, Interstate 71 west to the split to Louisville, and portions of Boone, Carroll, Gallatin, and Grant Counties.
5 The speed limit on the Ohio Turnpike is 70 mph.
6 In sections of I-10 and I-20 in rural West Texas, the speed limit for passenger cars and light trucks is 80 mph. Speed limits may be established not to exceed 85 mph if the highway is designed to accommodate the higher speed and it has been determined by a traffic and safety engineering study to be reasonable and safe, effective September 1, 2011.
7 Based on 2008 Utah House Bill 406, which became effective on May 5, 2008, portions of I-15 have a posted limit of 80 mph.
8 The posted limit may be as high as 70 mph where indicated by lawfully placed signs, erected subsequent to a traffic engineering study, effective 07/01/10.
KEY: n/a = not applicable.
NOTES: Interstates are divided into urban and rural sections based primarily on population size and population density. Many roads, particularly urban interstates, often have a lower posted speed limit than the maximum allowable shown in this table.
SOURCE: Insurance Institute for Highway Safety - Highway Loss Data Institute, Maximum Posted Speed Limits for Passenger Vehicles, available at http://www.iihs.org/laws/SpeedLimits.aspx as of Jul. 20, 2011.