As Iowa farmers will tell you, the only thing more important than growing their crops is having access to the markets to sell those crops. For many of our farmers across Iowa, market access depends on the ability to haul our goods down the Mississippi River, where the crops can be exported both domestically and internationally through the Gulf of Mexico.

In fact, more than half of all U.S. corn and soybean exports, including those grown and harvested by Iowa farmers, are shipped through...