The 1981 Professional Air Traffic Controllers Organization (PATCO) strike permanently changed U.S. labor relations and opened the door to the bitter, ideological polarization now rife in U.S. politics, a historian of the era says.

Georgetown University professor Joseph McCartin, author of Ronald Reagan, The Air Traffic Controllers And The Strike That Changed America, explained Reagan made strikebreaking and permanent replacement of workers acceptable.  It was legal but tacitly forbidden before.  After PATCO, firms become emboldened to smash workers and to strongly shove their agenda through Congress.

The first to grasp that were the airlines, who used the strike as an excuse to bust unions while adjusting schedules to increase their revenues.  Other businesses quickly followed Reagan's "permanent replacement" example and have done so ever since.