More, and larger trucks. Drive the interstates, Boston, MA, to the Pennsylvania, Ohio border. Each of those 50 footers, a lot of product, that can be delivered efficiently, Short haul, long haul, Short haul v.s. rail. Some custom loads are factory to job site in the construction industry. Cross into Ohio on the interstate system, you will see tandem trailers.
In general, a move away from any material handling system that was labor intense. IMO, Mike CT