The Dallas City Council voted to reduce the speed limit on a portion of U.S. 75 after NBC investigated the extreme speeds and speed-related crashes on that roadway.

NBC 5 Investigates clocked drivers at speeds above 120 and even 130 mph on a Monday evening.

Last fall, the NBC 5 Investigates series “Driven to Death” revealed that at least 18 people died and 78 more were seriously injured in speed-related crashes alone on Central Expressway in Dallas in less than five years.

NBC 5 Investigates has reported that the number of speeding tickets written on Central Expressway declined 70% from 2019 to 2021. That number increased in the next year but was still down about 30% compared to 2019 numbers.

So, since someone else did their job for them, monitoring traffic fatalities (that's someone's job, to monitor and report on those stats to the govt to adjust the speed limit appropriately) the Dallas City Council voted to reduce the speed limit, because with a lower speed limit (65) drivers could be arrested and their vehicles impounded at a lower speed threshold. 

https://www.nbcdfw.com/investigations/dallas-lowers-speed-limit-central-expressway/3643036/