Update (1144ET): President Biden and senior administration officials are working with others in the transportation industry, including truckers, shippers, and air freight, for "contingency plans" if a rail shutdown materializes at the end of the week, a White House official told Bloomberg. 

The administration is trying to understand what supply chains could be disrupted the most -- and how to utilize other forms of transportation to ensure commodities and consumer goods continue to flow across the country. 

More than 100,000 railroad workers could walk off the job on Friday if freight-rail companies and unions don't reach labor agreements. 

We noted that 29% of all US freight moves on the rails. Half the cargo is bulk commodities, such as energy, food, chemicals, metals, and wood productions -- the other half is shipping containers of consumer goods.