A Postal Service carrier delivers mail Monday in East Grand Rapids, Michigan. East Grand Rapids is one of the ares where mail service was suspended Wednesday.
CNN  — 

Neither snow or rain kept couriers from their appointed rounds during the Greco-Persian wars, apparently. But extremely dangerous wind chills will keep some US postal workers from theirs.

Brutally low temperatures and frightening wind chills (49 below zero in Chicago! 65 below zero in northern Minnesota!) led the US Postal Service to suspend deliveries Wednesday in parts of 10 states in the Great Plains and Midwest out of concern for workers’ safety.

The USPS listed the service suspensions by ZIP Code on their website. Basically, we’re talking about parts of:

• Illinois

• Indiana

• Iowa

• Michigan

• Minnesota

• Nebraska

• North Dakota

• Ohio

• South Dakota

• Wisconsin

About 212 million people – or 72% of the continental US population – will see temperatures drop below freezing over the next few days. And more than 83 million Americans – about 25% of the US population – will suffer subzero temperatures at some point between Wednesday and Monday.

While most of the Midwest will see frigid temperatures, Chicago will be “the epicenter of the extreme cold,” CNN meteorologist Dave Hennen said.

Chicago could reach a record low temperature of 27 below zero by Thursday morning. Its daytime high Wednesday is forecast to be 15 below zero.

CNN’s Faith Karimi and Steve Almasy contributed to this report.