Updated Feb. 4 at 10 a.m. ET
Extreme cold is forcing the U.S. Postal Service to shut down mail delivery in parts of 10 states in the Great Plains and Midwest, reflecting the perilous threat of a polar vortex that's bringing record-low temperatures and biting winds to a broad swath of the U.S.
"Some places could see wind chill readings as low as 60 below zero," the postal service said in announcing the rare decision to keep its mail carriers from making their rounds on Wednesday.