Gas prices in Massachusetts drifted further downward ahead of what’s expected to be the busiest Thanksgiving travel period in a decade. AAA Northeast on Monday reported that the average price of a gallon of self-serve, unleaded gasoline is $2.08, down 4 cents a gallon from last week. The group’s survey on Monday found prices ranged from $1.95 to $2.19 per gallon of self-serve regular unleaded. AAA estimated last week that close to 950,000 people from Massachusetts are expected to drive to Thanksgiving destinations, up 5.1 percent over 2015. – Michael Norton/ State House News Service