U.S. businesses are counting the cost of the deep freeze that has gripped swaths of the country, the latest economic disruption after the government shutdown.

Retailers and restaurants are facing a bill running to almost $1bn, according to one estimate, as Americans hunkered down at home to avoid icy cold that spread from the midwest to the north-east on Thursday.

At least 12 people were killed as temperatures broke records in some areas over the past few days, according to Reuters. Thousands of flights were canceled or delayed, rail lines were disrupted, and schools were closed in parts of Wisconsin and Minnesota. Power and water outages were reported in some areas.

Trade analysis group Panjiva Research said that the polar vortex could upend supply chains in the midwest. There was “significant rail and barge congestion” in Chicago and other parts of the region, it said.

Fertilizer maker Yara, steel producer Thyssenkrupp, and forestry products maker UPM-Kymmene were among the biggest industrial importers to the region, it said.

The overall cost to the economy was expected to be manageable, however, and smaller than an estimated $5bn bill from a polar vortex that hit in 2014.

Read more in the Milwaukee Business Journal.