Gas prices have jumped by 18 cents, the second-largest one-week increase since 1990, the AAA reports, second only to the September 2005 spike after Hurricane Katrina. The rise pushed the average U.S. gas price to $3.47 per gallon, and the Idaho average to $3.28 a gallon, AAA said; you can see their latest gas prices report here, including price comparisons in six Idaho communities.