All of Florida should have increased to 75 mph when it was brought into legislature years back. But of course, the governor shot it down because the police cried “safety”.
If you’ve ever driven in Florida, you know that traffic is moving a minimum of 80 mph, a lot of times pushing 90 mph, on all the 70 mph interstate highways and the Turnpike. A 75 mph speed limit would not be unreasonable nor result in much changes to traffic flow, IMO. It would just be closer to reality.
Tennessee used to have 75 mph rural interstate highways pre-1973. I’m not sure what’s keeping them from going up again from 70 mph, most of the highways can easily handle it. With Arkansas now at 75 mph, it only makes sense Tennessee follow. I-40 east of Memphis can just as easily handle a 75 mph limit as I-40 west of Memphis presently does.
And for crying out loud - please eliminate the “environmental” speed limits in place near Memphis, and also on I-81 and I-26. At minimum, both highways should be posted at 70 mph throughout (perhaps the exception I-26 near Johnson City). I’m aware I-26 used to have 70 mph zones until lowered due to “safety”. Again, 65 / 55 mph does nothing to slow down traffic, make a safer environment, or cut down on “air quality”. Traffic still flows in excess of 80 mph (when there’s not walls of trucks) at least in the case of I-81. When I drove I-26 in the past, traffic was flowing at least around 75 mph, pushing 80 mph at times. Even more in the southern stretch, where the random 55 mph limits there are even more absurd.
As for Memphis, replace the 65 / 55 mph zones with 70 mph (I-40, I-55, I-269, TN-385) including the northern beltway around the city, and bump I-240 from 55 mph to 65 mph.
Nashville at least gets it right in keeping limits at 70 mph throughout, with the exception of right near the city center. Knoxville took a major step forward in eliminating all environmental limits, and bumping those long, absurd 55 mph zones on I-40 to 65 mph (60 mph near Downtown), though reasonably they could go to 70 mph west of Downtown to the I-75 split.