Where have all the cows gone?

Over past the half century or so, there has been a dramatic shift in where most of the cattle in the U.S. are feed just prior to slaughter.  Using data from USDA-NASS, I calculated the percentage of all U.S. cattle on feed that were in 6 selected states at the beginning of January each year from 1965 to 2005.

The story is familiar to industry analysts.  Over this time period, cattle largely moved from the upper Midwest (Iowa and Illinois) to drier climates in Texas, Oklahoma, and Kansas.  Whereas 19% of cattle on feed were in Iowa in 1965, the figure was only 8% by 2005; by contrast only about 5% of cattle on feed were in Texas in 1965, but around 20% were in the state by 2005.  Whereas only 47% of all US cattle on feed were in these six states in 1965, concentration had increased as 67% of all cattle were being fed out in these six states by 2005. Stated differently, if you eat a steak today, there's a roughly two-thirds chance it came from a cow that was fed in Iowa, Nebraska, Illinois, Kansas, Oklahoma, or Texas.  

The trends in the above figure might appear to be something of a paradox because Iowa, Illinois, and Nebraska grow a lot more corn (i.e., cattle food) than Kansas, Oklahoma, and Texas.  But apparently the economics were such that it made more sense to ship to corn (and the cattle) to drier climates and locations where large packing plants could be situated far away from population centers.  

I'm wondering if this trend is starting to change, even if just by a little bit.  Beginning in the early to mid 2000s, US policy started to encourage corn-ethanol production in a big way.  Now, all that corn didn't need to travel to cows, it could go to all those ethanol plants which began popping up around the upper Midwest.  Here's a graph of the percentage of U.S. corn use that went to ethanol production from 2000 to 2012 (data are from the Feed grains yearbook, USDA-ERS).

Such a dramatic shift in the use of corn must have had some effect on cattle feeding.  Perhaps even in the geographic location of cattle.  According to a least one source, the largest producers of ethanol in 2015 were Iowa (at 3,820 million gallons/year capacity), Nebraska (1,976 gallons), and Illinois (1,525 gallons).  Much further down the list were Kansas (529), Texas (381 gallons), and Oklahoma (no capacity reported).  

Often lost in the discussions of food waste is the acknowledgement that cattle (and other livestock) are often big consumers of what would otherwise be waste products.  In this case, cattle can eat so-called distillers grains that are byproducts of ethanol production.  However, this distillers grain is not as easy or cheap to transport.  Thus, the economics might have shifted a bit toward bringing the cattle back closer to their finishing food.  

Here's the same graph as the one above but for the more recent time period from 2005-2016.  

There aren't dramatic geographic shifts, but the trends are consistent with the idea that ethanol has altered the geographic location of cattle finishing. Fitting a linear trend line through each state's data over this time period indicates that the states heavy with ethanol production have gained cattle and states with relatively little ethanol production have lost cattle.  Iowa, Nebraska, and Illinois have increased their share of the US cattle on feed inventory by an average of 0.11%, 0.11%, and 0.05% per year over the last 11 years.  By contrast, Kansas, Oklahoma, and Texas have decreased their share of the US cattle on feed inventory by an average of -0.13%, -0.04%, and -0.09% per year over the last 11 years.

Obviously a lot has changed during the past 10 years other than ethanol production (drought and lower overall cattle inventories come to mind), but this might be a factor contributing to the spatial location of cattle in the US.