CHICAGO, IL — With school districts, libraries, government offices and even local businesses shutting down due to the life-threatening cold weather Wednesday and Thursday, the U.S. Postal Service made the extremely rare decision to halt mail delivery in several states, including portions of Illinois. As the polar vortex brings wind chill values of -55 degrees to parts of Illinois, the USPS said it is suspending mail delivery in parts or all of Chicago, central Illinois, western Illinois, Indiana, Minnesota, Michigan, Iowa, and western Wisconsin.

“While the goal is to finalize mail delivery to every customer, variables such as challenging weather conditions may affect delivery times,” USPS said in a statement, according to WGN. “Under severe extreme conditions, including extreme cold, mail delivery may be curtailed with plans for next delivery day. The safety of employees is always the main priority.”

The postal service issued the announcement Tuesday afternoon, saying service in some areas would be halted “due to projected deteriorating weather conditions related to Polar Vortex Jayden,” adding, “Retail operations at local offices will be available, but may be limited. There will be no collection mail pick up from businesses or collection boxes. Additionally, there will be no residential or commercial package pick-up services. The Postal Service receives no tax dollars for operating expenses and relies on the sale of postage, products, and services to fund its operations.”

Delivery was also suspended in South Dakota, portions of Montana, Kansas, Missouri, and Nebraska, according to news outlets.