If Silicon Valley gets its way, it won't be long until every vehicle in the country has nobody behind the wheel.

Driverless car technology is expected to reduce labor costs, fuel costs and accidents, but it will also be a complete disaster for the millions of Americans who work as long-haul truckers, bus drivers or cab drivers. Truck driving alone is the most common job across vast swathes of the United States, and they could all be unemployed within years.

Almost 3 percent of all working American are drivers of some sort — more than 2 percent are truck drivers, 0.4 percent are bus drivers and 0.3 percent are cabbies and other types of drivers, according to Census Bureau occupational data. But those jobs aren't evenly distributed across the country, and some places are going to get slammed by the automation of jobs more than others.