The weather system, which started as rain from Mexico but has since turned into snow, is forecast to affect an 1,800-mile (2,900 km) swath of the United States from Colorado to the Mid-Atlantic.
The storm hit Kansas and Missouri on Friday and pummeled those states again on Saturday as it extended into parts of Iowa, Illinois, Indiana and Ohio, said U.S. Weather Prediction Center meteorologist Andrew Orrison.
In Kansas City, snow dusted the field at Arrowhead Stadium during Saturday's National Football League playoff game between the hometown Chiefs and Indianapolis Colts.
The storm is leaving its heaviest snowfall on areas west of St. Louis, where about a foot and a half of snow was recorded, with still more falling on Saturday, Orrison said.
At least five people died in weather-related crashes on roads in Missouri and Kansas, according to the highway patrolmen in both states.
Dozens of flights were canceled at St. Louis Lambert International Airport, which described the onslaught of snow on Twitter as one of its biggest single-day winter storms in years.
Snow is forecast for the Appalachian Mountains and the Mid-Atlantic on Saturday evening and Sunday.