The sustainability of animal agriculture is currently one of the most highly-debated issues within food production. Consumers often have an ideological view of the perceived advantages of historical small-scale agrarian systems compared to modern agriculture, which, in combination with a renowned desire to understand how food is produced, leads to the supposition that the “good old days” were environmentally superior. Through improvements in genetics, nutrition and management between 1977 and 2007, the U.S. beef cattle industry increased average slaughter weight (1,338 lb in 2007 vs. 1,032 lb in 1977) and overall growth rate (2.60 lb/d in 2007 vs. 1.59 lb/d in 1977) which resulted in the total average days from birth to slaughter being reduced from 609 d (1977) to 485 d (2007). In combination, these productivity improvements resulted in considerable reductions in feed (19%), land (33%), water (12%) and GHG emissions (16%) per lb of beef over the thirty-year time period.