Montana has declared an emergency after a rare September snowstorm dumped as much as two feet of snow, causing dangerous driving conditions and scattered power outages.
Winter storm warnings were posted for parts of western Montana, northern Idaho and northeast Washington.
Snow was also forecast for areas in Wyoming, Utah, Oregon, Nevada and California.
The brunt of the storm hit Montana where up to 61cm (2ft) of snow fell on Saturday in the mountains and a record 35.5cm (14in) fell in Great Falls, with snow still falling on Sunday.
Montana Governor Steve Bullock declared the emergency on Sunday, allowing the state to mobilise resources to help the affected areas.
He said: "With an unprecedented winter storm throwing our state a surprise in September, state and local governments are working closely together to protect the health and safety of Montanans and our top priority is making sure that happens.
"Montanans should heed all warnings from state and local officials, travel safely, and be cautious during this time."