UNDATED (KDAL) - Gas prices made the move to over 4 dollars a gallon throughout the Twin Ports and much of the upper midwest yesterday. According to AAA Minnesota spokesperson Gail Weinholzer the recent spike in prices can be traced to two Chicago area refineries that shut down for maintenance and won't resume operations until after Memorial Day. She says no relief at the pump should be expected until mid summer. Most Duluth stations are now charging from 4.09 to 4.19 a gallon for regular unleaded, while some Superior stations are up to 4.29. The average price in Minnesota is 4.08 while Wisconsin's average is at 3.86.