There are fewer cows, and fewer dairies, in the United States today. But each cow produces nearly twice as much milk as it did in 1985, up from 12,000 lbs/year to 21,000. This is kind of incredible, and the USDA projects that cow production will continue to increase. The reasons are largely related to changes in what we feed cows (more nutritious food, more of it), breeding, and some technological advances. It’s worth noting, though, that while each cow produces more per year, the number of years a high-producing cow can produce for is only about four; so we have higher cow turnover (more dairy cows turned into hamburgers) than we once did, at least on farms who heavily milk their cows. (Organic farmers I’ve spoken with report lower volumes of milk production per cow per year, but their cows milk for more like a decade)