Hauling an estimated 11 billion tons annually and handling nearly three quarters of the nation’s freight by weight, there can be few doubts about the importance of the nation's truckers to the economy. "America’s truck drivers are essential to the strength of our economy, the security of our nation, and the livelihoods of the American people," the White House said earlier this year . And for the drivers themselves, carting cargo on America’s highways has been an engine of class mobility—a