This article orginally appears on Chron.

Out of sight, out of mind. That pretty well sums up the layperson's view of the country's extensive inland waterways system, an efficient, environmentally friendly network of rivers, locks and canals that moves our huge fleet of floating pack mules, aka barges, powered by towboats.

And what gets moved? Let's take Texas: The 400 miles of the Gulf Intracoastal Waterway connects Houston with ports from Beaumont to Brownsville. In 2011, commodities from coal to grain, aggregate and iron ore to chemicals and crude petroleum totaling nearly 20 million tons moved through the system. The dollar value of these goods was nearly $70 billion, according to statistics from the U.S. Army Corps of Engineers.

Read the full article here.