Power cuts and travel misery in US and Canada amid freezing winter storm

More than a million people in darkness and thousands of flights cancelled amid lows with wind chill of -55F (-48C)

More than a million people in the US are in the dark after a bomb cyclone" winter storm struck the country, closing highways, grounding flights and causing misery for Christmas travellers.

Heavy snow, howling winds and air so frigid it instantly turned boiling water into ice took hold of much of the country, including normally temperate southern states.