One of the peculiarities of our high-tech society is that much of what sustains it is invisible or simply unnoticed by most of us most of the time. We flick a switch and the lights come on. We drive to the supermarket and find the shelves stocked to overflowing. How all this is made possible doesn't usually rate a second's thought.

The Port of Los Angeles and nearby Port of Long Beach are enormous and complex operations with a simple goal: to import and export (mostly import) vast amounts of stuff as efficiently and effectively as possible. Sprawling across 10,700 acres of Southern California waterfront—an area fifteen times the size of Central Park—they are the two busiest ports in the country, together accounting for 40 percent of waterborne cargo in the United States, more than half of which ends up east of the Rockies. In 2008, the Port of Los Angeles alone was responsible for $243.7 billion of global trade. Five days a year—Labor Day, Thanksgiving, Christmas, New Year's Day, and "Bloody Thursday," a holiday commemorating two strikers killed in the 1934 West Coast Longshoremen's Strike—activity at the two ports grinds to a halt. But one imagines that the cargo vessels and tugboats, dozens of cranes, thousands of trucks, and 500,000 people who work at the ports are not at rest on Bloody Thursday, merely idling in neutral.

So dependent is our economy on the cargo flowing through the Ports of Los Angeles and Long Beach that a biological metaphor is appropriate. On a helicopter tour of the area, Bill Sharpsteen follows the Alameda Corridor, a 20-mile railroad expressline that connects the Port of Los Angeles to the transcontinental railroad network. The port, he reflects, is a massive heart, pumping what the country needs, or wants, through this major rail artery, which eventually separates out into thousands of smaller vessels and capillaries. And indeed, from the air, it has that appearance, an industrial vascular system whose disruption would cause an economic heart attack for the country.

Thus, a no-work holiday is the heart of commerce skipping a beat, a palpitation that can be planned for and lived with. What will concern you after reading The Docks, Sharpsteen's new book about the Port of Los Angeles, are the unplanned events—labor disputes, terrorist attacks and other security emergencies, financial crises, and environmental repercussions—that have the potential to bring the national economy to its knees, because the Port of L.A. connects Chicago to Hawaii and South Carolina to South Korea and China to everyone. It's happened before. A ten-day West Coast lockout in 2002 cost the U.S. economy up to $15 billion while ships full of rotting food sat anchored out at sea.

The images most Americans have of a modern port are of eight-story hammerhead cranes and multicolored shipping containers stacked five-high at a terminal waiting to be loaded on to a truck or train or shipped empty back to Asia. But in The Docks, Sharpsteen introduces us to the people behind (and below) those images. Thousands of cargo vessels enter the Port of Los Angeles every year, and bringing in each one involves about 200 steps coordinated among dozens of different entities. Sharpsteen talks to the port administrators, shippers, longshoremen, pilots, clerks, chandlers, tugboat captains, truck drivers, Coast Guardsmen, Customs and Border Protection agents, and port police who keep the docks running smoothly, profitably, and safely. He describes too how the docks have changed in the last fifty years. He interviews retired longshoremen who remember when discharging a ship's cargo required five to eight gangs of eight "hold men" each, back when a ship might be in port for five days while it was unloaded and reloaded, before mechanization reshaped the industry in the 1950s and 1960s. (Now a ship is in port for just two days.) He tells the story of the women who at great physical risk integrated the International Longshore and Warehouse Union in the 1980s.

Less visible but no less important are the community activists who try to keep their powerful neighbor accountable. Sharpsteen talks with a mechanic protesting the aesthetic impact of the port, a university professor studying the health effects of the port's "Diesel Death Zone," and the eco-attorneys who won an important case requiring many ships to plug into the electrical grid rather than continuously run their polluting engines. The Docks could easily have read like a bureaucrat's report, dry and groaning under the weight of statistics. Instead, in a mosaic of evocative stories and vivid images (Sharpsteen is also a photographer and award-winning documentary producer), the world of the port comes alive.

Early in the book, Sharpsteen compares the Port of Los Angeles to the electric company. Both are rarely considered in our daily lives. As long as the refrigerator hums quietly, as long as we can still get cheap toys at Wal-Mart, our favorite Australian wine at the supermarket, and Brazilian oranges in winter, why worry? But it's worthwhile to remember that our appetite for imports—not to mention the world's comparatively smaller appetite for our exports—is being fed by the machinery of industry and hundreds of thousands of proxies. To read The Docks is to be mindful of those proxies and honor their work, even as we ask hard questions about what it means to be addicted to cargo "pumping through a single, vulnerable port." Because sooner or later the lights aren't going to turn on, and then what?

John Pattison is the co-author of Besides the Bible: 100 Books that Have, Should, or Will Create Christian Culture (Biblica, 2010). He lives with his wife and daughter in Silverton, Oregon.

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