This week marks the beginning of the busiest travel time of the year. For millions of Americans, the misery of holiday travel is made considerably worse by a government agency ostensibly designed to make our journeys more secure. Created in the wake of the Sept. 11, 2001, attacks, the Transportation Security Administration has largely outlived its usefulness, as the threat of a terrorist attack on the U.S. homeland continues to recede. These days, the TSA’s major role appears to be to make plane trips more unpleasant. And by doing so, it’s encouraging people to take the considerably more dangerous option of traveling by road.