Meteorologists expected one to three inches of snow through Friday tonight, with the heaviest portions falling earlier during rush hour.
The roads were already treated with salt.
Snow emergency plans went into effect at noon in Allegany County and 3:00 in Frederick and Washington counties.
The areas that freeze up first are the bridges. Police say it's the overpasses on Interstates 81 and 70 that see the most accidents because those elevated roadways get slick first. I-68 also had several cars sliding off the road during the snowfall.
"We try to get some of it off before it starts to accumulate too much because then the cars will pack it down and of course it'll freeze," says Ed Plank of the Washington County Highway Department. "Sometimes it works to our advantage sometimes it doesn't."
Crews say it usually takes about eight to 12 hours after the snowfall to fully clear the roads.