OTTAWA, IL  – Gas prices are on the rise, though LaSalle County still has about the lowest prices in North Illinois.  According to AAA, gas prices in Illinois rose nearly 20 cents in the past month.  LaSalle County has the 2nd lowest average gas prices in North Illinois, nearly 18 cents lower than the state average of $2.31 a gallon. Only Ogle County, with prices a penny less per gallon, is cheaper than LaSalle County in the region.    Gas prices for the state are lower than they were pre-pandemic, coming in at nearly 57 cents cheaper than it was a year ago.