Four railroad unions have joined together to vote down a labor deal from freight railroad carriers, setting a coordinated strike deadline of December 9 if they can't reach an agreement. If the freight lines are interrupted, virtually every industry will be impacted within a matter of days.

On Tuesday, November 22, the Brotherhood of Railroad Signalmen (BRS) announced that it would be postponing its strike deadline to align with three other unions, the Brotherhood of Maintenance of Way Employees (BMWED), the International Brotherhood of Boilermakers, and SMART-TD.

Rail unions that have agreed to carrier contracts say they won't cross the striking workers' picket lines, meaning the strike would likely be industry-wide.

The four unions are holding out on a better agreement primarily in an effort to secure 56 hours of sick time per year. That would bring rail workers' benefits in line with those guaranteed to federal contractors.

The Association of American Railroads (AAR), an industry group representing all major North American freight carriers, has provided an explanation for why it doesn't offer workers designated paid sick days, arguing that it's a part of "the nature of railroading". The group also wrote that the employees who are "subject to variable or on-call work schedules" are "almost exclusively" the highest-paid rail workers.

"Although the terms vary from one railroad to another, all railroads have work rules and policies designed to balance employees' need to take time off with the need to maintain safe, ongoing operations," the AAR wrote.

"All work rules and time off entitlements result from voluntary collective bargaining agreements between the railroads and the labor unions representing rail workers, and most of these have been in place for many decades," the group continued.

According to the AAR, each day that rail workers are on strike would cost the U.S. economy up to $2 billion.

The group has until Dec. 9 to come up with an agreement that the unions will accept, but rail workers will actually begin to prepare for the strike a week before it's set to take place. First, workers begin to prioritize security-sensitive shipments, including chlorine for drinking water as well as other hazardous materials. Then, four days before the strike's official start, workers will stop the transportation of all chemicals.

If an agreement isn't reached by the end of those four days, union workers will either stage a strike or a lockout. At that point, under the Constitution's Commerce Clause, Congress could step in to create a labor agreement and end the strike.