Kate Golden of the Wisconsin Center for Investigative Journalism had a hunch that Wisconsin cows were something special. Taking a look at some National Agricultural Statistics Service data, she found that despite a nearly constant decrease in the number of cows on Wisconsin dairy farms, milk production has increased steadily.
About this Viz
As you can see from the bottom chart, milk production in Wisconsin has increased from 10B gallons in 1924 to over 25B in 2009. The amazing thing is that the number of cows has dropped nearly 47%! This explains the almost logarithmic growth curve in production per cow, shown in light blue. Go bessie go!
Note: Mark Perry did a great riff on this viz by combining it with some milk price data. You can see the viz on his blog, Carpe Diem.
