Some gas stations are selling it for nearly $6.
Overnight, prices jumped as much as 20 cents a gallon.
Recent refinery fires in California and pipeline problems are blamed for the spike.
California reserves have also hit a 10-year low, forcing some stations to shut down their pumps.
The national average for gas is about $3.79.
In the Chicago area, prices are hovering around $4 a gallon.
