With certain rare exceptions, (local-haul gravel trucks and some RV's) large trucks and RV's are prohibited from using US-93 over the Hoover Dam. Ever since 9/11 all trucks headed for I-15 must use Arizona county route 68 thru Laughlin and then north on US-95.

So it is just cars, SUV's and motorcycles on the route for most of the last couple of years.