One Percheron historian attributes this popularity to the breed's "strength, energy, activity, robustness and endurance".[24] After World War II, increasing mechanization prompted a decline in the Percheron population.[3] In 1954, only 85 Percherons were registered in the US, a record low.[11] The 1950s, 1960s and early 1970s were bad years for the US Percheron population, and breeding was reduced to only a few farms.