On Monday this week, one of the biggest rail unions joined three other unions that have rejected the deal facilitated by the Presidential Emergency Board. Train conductors represented by the Sheet Metal, Air, Rail and Transportation Workers-Transportation Division, or SMART-TD, narrowly rejected the proposed deal. The vote drew record turnout among the union’s membership of more than 28,000 conductors and other workers. SMART-TD is one of four freight rail unions that have rejected the deal, while eight other unions have approved it. This raises the risk of a strike, which could start as soon as Dec. 9 under a deadline that was pushed back Tuesday. The dependence on the already-suffering rail system would be tested, especially with other circumstances affecting the supply chain, like a Mississippi River drought affecting much of the midwest. United States Secretary of Transportation Pete Buttigieg said the Biden administration’s goal is to make sure a strike doesn’t happen.