In our series on the Ports of Indiana, we’ve seen steel and manufacturing hubs on Lake Michigan and the Ohio River. Today, we go to Indiana’s truest river port – Mt. Vernon, outside Evansville. It’s the highest-traffic port in the system, helping move processed grain, coal, and more all around the world. Indiana Public Broadcasting’s Annie Ropeik reports it’s also more susceptible than any other state port to the fallout from shifts in federal policy.