Chicago's O'Hare airport had already seen six inches of snow as of mid-afternoon and heavier accumulation was reported in Minnesota and Iowa.

BBC: Snowstorm strikes US Midwest on way to east coast

On Tuesday, schools were cancelled across Wisconsin, Minnesota and Illinois, and as much as 9in of snow was reported at Chicago's busy O'Hare airport by midnight.

BBC: US government shuts down ahead of winter snow storm