This post on CD displayed two maps showing each US state’s largest country trading partner for exports and imports in 2016. In response to a comment on those state maps, the table below shows something that is potentially very interesting: the degree (importance) of international trade for each US state in 2015. The table shows GDP for each US state (data here), the total trade volume (exports + imports, data here),and the volume of international trade activities as a share of each state’s GDP in 2015, ranked from highest to lowest. Ignoring the District of Columbia, the average trade share for US states in 2015 was 17.7%, and ranged from a low of 5.3% for South Dakota to a high of 38.0% for Michigan.

Following Michigan, the US states with the next highest trade shares in 2015 were Louisiana (35.1%), South Carolina (34.8%), Tennessee (34.7%), Kentucky (34.3%), Washington (30.9%) and Texas (30.7%). I’ll follow up on these data with a shaded map based on trade shares by state, update the data when 2016 state GDP data are available later this year, and possibly provide further analysis, but for now, here are my initial thoughts on the US states with the highest trade shares in 2015, and the policy implications of those trade shares:

1. Michigan. The auto industry clearly explains the importance of international trade to the US state economy that is the most highly globalized. Auto-related exports represented nine of the top 10 state export categories for Michigan in 2015, and all of the top 10 state imports. Michigan’s top import trade partner is Mexico and its top state export trade partner is Canada, reflecting the fact that Michigan automakers buy a lot of auto parts from Mexico and they then sell a lot of cars to Canada. Partly thanks to NAFTA, the North American auto industry relies increasingly on cross-border supply chains for parts, supplies, materials, and finished products. Exhibit A: For 2016 models, the average foreign content for GM’s fleet of vehicles sold in the US was 55.4% (not counting Canada according to government labeling rules, which counts the percentage of “U.S./Canada equipment content” together as “domestic content”) and the average foreign content was 53% for Ford vehicles. In contrast, the average foreign content for Honda vehicles sold in the US last year was less than 50%. The globalization of the auto industry blurs the distinction between “domestic” and “foreign” cars and makes that distinction increasingly irrelevant.