Trailers

Increasing truck size and weight without sacrificing safety required two synchronized developments:

1. Trailer Length Expansion

   • In 1959 alone, ten states legalized 40-foot trailers, up from the earlier 30- to 35-foot norms, enabling carriers to boost payload by 25–30% per run.

   • Standardization efforts in the early 1960s harmonized dimensions across state lines, reducing detours and logistical headaches for long-haul fleets.

2. Air-Actuated Braking Systems

   • George Westinghouse’s 1872 patent for the automatic air brake revolutionized rail safety—and by 1925, air brakes became standard on heavy trucks, offering instant, uniform stopping power across all axles.

   • Postwar improvements in compressor design and valve technology made brakes more responsive and easier to maintain, giving drivers the confidence to handle fully loaded trailers at higher speeds and on steeper grades.

Together, longer trailers and reliable air brakes unlocked economies of scale for the trucking industry, lowering per-unit shipping costs and helping trucking outpace rail for many commodities by the mid-1960s.