<P> Speed limits in the United States are set by each state or territory . Highway speed limits can range from an urban low of 35 mph (56 km / h) to a rural high of 85 mph (137 km / h). Speed limits are typically posted in increments of five miles per hour (8 km / h). Some states have lower limits for trucks and at night, and occasionally there are minimum speed limits . Most speed limits are set by state or local statute, although each state allows various subdivisions (counties and municipalities) to set a different, generally lower, limit . </P> <P> The highest speed limits are generally 70 mph (113 km / h) on the West Coast and the inland eastern states, 75--80 mph (121--129 km / h) in inland western states, along with Arkansas and Louisiana, and 65--75 mph (105--121 km / h) on the Eastern Seaboard . Alaska, Connecticut, Delaware, Massachusetts, New Jersey, New York, Puerto Rico, Rhode Island, and Vermont have a maximum limit of 65 mph (105 km / h), and Hawaii has a maximum limit of 60 mph (97 km / h). Washington, D.C. and the U.S. Virgin Islands have a maximum speed limit of 55 mph (89 km / h), and Guam and the Samoa have speed limits of 45 mph (72 km / h). Unusual for any state east of the Mississippi River, much of I - 95 in Maine north of Bangor allows up to 75 mph (121 km / h), as well as up to 600 miles of freeways in Michigan . Portions of the Idaho, Montana, Nevada, South Dakota, Texas, Utah, and Wyoming road networks have 80 mph (129 km / h) posted limits . The highest posted speed limit in the entire country can be found on the Texas State Highway 130, and it is 85 mph (137 km / h). </P>

Who sets the reasonable safe speed limit on any roadway