Almost every time we get on an interstate highway or major road, we see the most visible cogs in the U.S. distribution system — tractor-trailer trucks. And anyone who’s ever been stuck for several minutes waiting for a long freight train to pass can appreciate how much freight moves on U.S. railroads. But most Americans would be astounded at the amount of freight that moves through a few dozen ports along the East and West coasts and some of the country’s major waterways. The numbers are staggering: the equivalent of 28.74 million containers measuring 20 feet long by 8 feet wide by 8.5 feet high passed through the 30 busiest U.S. ports in 2009 (the latest year for which statistics are available). If those containers were stacked end to end, they’d stretch some 111,000 miles, nearly half the distance to the moon. Here’s a look at the 10 busiest U.S. ports based on container traffic, according to the 2012 Statistical Abstract of the United States.