Gas prices in most of the East Valley dropped over the last week, but drivers filling up in Scottsdale saw an increase.

East Valley prices are at an average $4.52 a gallon this week, down from $4.54 a week ago. Scottsdale pump prices ticked up to $4.73 from $4.72, according to AAA Arizona, which calculates prices for both regions separately.

AAA also combines Phoenix and Mesa for a gas price average: $4.50 this week compared with $4.52 a week ago.

Arizona’s average price stands at $4.25 a gallon, down a penny from a week ago, AAA reported.

The national average remained flat over the past week at $3.80.

AAA officials said fluctuating oil prices have limited price increases despite tighter supply and “robust gasoline demand” – factors that typically push prices higher.