Friday, November 27, 2009

Fun Friday: Where Does Thanksgiving Dinner Grow?

"When far-flung families get together for Thanksgiving dinners, much of their food will have logged more miles than their relatives and friends around the table," according to the Worldwatch Institute, who recently released a new study titled Home Grown: The Case for Local Food in a Global Market.

Linda Zellmer, a Government Information and Data Services Librarian at Western Illinois University, has created a series of maps showing where many of the common ingredients in a traditional Thanksgiving meal are grown.  The maps were created with GIS using data obtained from the 2007 Census of Agriculture, as discussed in yesterday's post. Check out all of her Thanksgiving Maps & Posters on her website.  She even provides downloads of the data she used, so you can try creating your own maps! (Click on the map below to see the original.)

Curious how these individual maps might add up together, we downloaded Linda Zellmer's data and created a summary map of all the Thanksgiving crops.  While most crops were measured in acres harvested, turkeys were measured in shear number and wheat was measured in bushels harvested, making a direct sum of all crops difficult.  Instead, we calculated the fraction of each crop grown in each state and summed those fractions to create a Thanksgiving Food Production Index of sorts, symbolized in six classes using natural breaks, resulting in the map below.  For example, if one state grew 10% of the sweet potatoes, 2% of the turkeys and 4% of the wheat, it's index score would be 0.16.  Since the index is a fairly meaningless number on its own, a legend was not included.

To account for the enormous difference in size between Texas and Rhode Island, we then took the Thanksgiving Food Production Index and divided by the area of each state, resulting in the map below.  Though Massachusetts, New Jersey, and Delaware may not account for a large percentage of crops, due to their small size, their percentage of crops per area is just as big as the largest state producers.


So where did your Thanksgiving dinner grow?  While California, Wisconsin, and Tennessee seem like likely candidates, the answer could be just about anywhere in the U.S. or even abroad.  There are definitely severe economic and environmental implications of transporting food such long distances; however, there is something appropriate to the Thanksgiving spirit that the food on your one table could have been harvested from every state in the country.