Driving remains challenging in northeast Kansas as workers struggle to keep roads clear of snow driven by strong winds.

Interstate 70, which was closed on Wednesday, was reopened across the state early Thursday. But U.S. 183 north into Nebraska and U.S. 36 in northwest Kansas remain closed.

Kimberly Qualls, a spokeswoman for the Kansas Department of Transportation, told KMBC-TV that many roads were snow packed and travel remains difficult, particularly in northeast Kansas. She says the high winds were blowing snow back onto roads as soon as it’s removed, causing several vehicles to slide off roads.

More than 30 schools called off classes across the state, with some opening late.