what is the speed limit on i 40 in tennessee
Speed limits in the United States by jurisdiction Tennessee generally posts its rural interstates at 70 mph. These include all of the state's two-digit Interstates except Interstate 55 and Interstate 26. The only auxiliary interstates in Tennessee with a 70 mph speed limit are Interstate 155 and Interstate 840. 70 mph speed limits are allowed on all other controlled access highways, and are found on controlled-access portions of U.S. 51 and S.R. 22, 111, 386, and 396. In 70 mph zones, the default minimum speed limit is 55.[157] Urban interstates are generally posted at 55 to 65 mph, however, portions of Interstates 24, 40, and 65 and S.R. 386 in Davidson County, as well as I-24 in Clarksville are posted at 70 mph. Four-lane divided highways are posted as high as 65 mph but are sometimes 55 mph. These are often hotbeds for speed camera enforcement leading into a municipality.[citation needed] 55 mph speed limits are allowed on two-lane state maintained roads, but some contain 45 and 50 mph limits, even in rural areas, primarily as a result of local policies. In East Tennessee, most mountain roads leading to North Carolina are poorly posted at 45 mph. Furthermore, two-lane roads such as US 321 and S.R. 91 have the same mountain and road width characteristics when leaving Tennessee into North Carolina or Virginia at 55 mph.[citation needed]
National Maximum Speed Law Congress lifted all federal speed limit controls in the National Highway System Designation Act of 1995, returning all speed limit determination authority to the states effective December 8, 1995. Several states immediately reverted to already existing laws. For example, most Texas rural limits that were above 55 mph (90 km/h) in 1974 immediately reverted to 70 mph (115 km/h), causing some legal confusion before the new signs were posted. Montana reverted to non-numerical speed limits on most rural highways, although its legislature adopted 75 mph (120 km/h) as a limit in 1999; as a result, according to Insurance Institute for Highway Safety researcher Anne McCartt, "What's impressive is the huge drop in the percent of vehicles going very fast...The proportion of vehicles exceeding 75 mph, the limit set [by Montana] in 1999, tumbled 45 percent. The proportion surpassing 80 mph plummeted 85 percent. Large trucks slowed, too." (She did not mention that the IIHS survey of traffic speeds on Interstate highways in 2006 she referred to, found Montana, as compared with New Mexico and Nevada, had the highest compliance with the 75 mph speed limit on rural interstates: 76 percent.)[51] Hawaii was the last state to raise its speed limit when, in response to public outcry after an experiment with traffic enforcement cameras in 2002, it raised the maximum speed limit on parts of Interstates H-1 and H-3 to 60 mph (95 km/h).[52]