Workers in four unions have rejected a tentative contract deal announced in September, while eight approved it."Therefore, absent a voluntary agreement, we call on you to take immediate steps to prevent a national rail strike and the certain economic destruction that would follow."A rail traffic stoppage could freeze almost 30% of U.S. cargo shipments by weight, stoke inflation and cost the American economy as much as $2 billion per day by unleashing a cascade of transport woes affecting U.S. energy, agriculture, manufacturing, healthcare and retail sectors.Last week, the U.S. Chamber implored lawmakers to step in one day after members of the country's biggest railroad union rejected a tentative agreement.President Joe Biden's Presidential Emergency Board in August released the framework for the tentative deal forged in September between major carriers like Union Pacific Corp (UNP.N) and a dozen unions representing 115,000 workers."