Dumb Speed Limit

                I recently drove from Memphis to Nashville on Interstate 40.  I drive this route often.  But there is one section of the road that is one of my pet peeves. When finally leaving the suburbs of Memphis and the interstate narrows from three lanes to two lanes on each side, the speed limit is 65 mph.  Then you pass exit 25 which is the last exit in the Memphis area.  There are no more entrances or exits to the interstate until you reach exit 35 ten miles away.  Now for several miles on this stretch of highway, the speed limit remains at 65 mph.  Suddenly, it goes to 70 mph.  So what has changed on the highway?  There were no more exits or entrances, no construction.  Why does the state not change the speed limit to 70 immediately after exit 25?  The reason is obvious—the county line.  As soon as you leave Shelby County, the speed limit goes to 70 mph.  Now in our day of modern intestates, why should a county line be used to determine a speed limit.  Common sense would say that the highway conditions, density of entrances or exits creating change in the amount of traffic or other reasons directly affecting traffic would be the factors that determine the speed limit.  But no, here we let the unnoticeable county line on a map determine the speed limit.  It would seem the speed limit between exits 25 and 35 would be the same all the way.  I just saying…..