In the June 29, 2016, Miner there was an article by Doug McMurdo titled "Speed adding to Arizona death toll."
While the specific crashes were on other highways, I have some comments about speed on U.S. Highway 93 between Kingman and the Nevada state line.
Essentially this entire segment is a divided roadway with a posted speed limit of 65 mph. I drive this roadway frequently and observe that most traffic significantly exceeds the speed limit, especially on weekends.
Several times during the past year I have driven from Boulder City to Kingman on Sunday afternoon. I almost always set my cruise control at 70 mph.
One Sunday I was passed by 126 vehicles and I passed four vehicles between milepost 20 and Coyote Pass. I would conclude that at that time 127 vehicles were exceeding the speed limit and 126 of them were going more than 5 mph over the speed limit. Some were obviously going much more than 70 mph.
I saw one Highway Patrol vehicle a few miles north of Coyote Pass. Other Sundays when I counted vehicles the numbers have been similar. I have to conclude most Sunday drivers ignore the posted speed limit on this portion of Highway 93, and the state has little interest in enforcing the speed limit.