The national average price of a gallon of regular unleaded remained flat at $2.29 per gallon for the week ending March 20, as drivers are now paying about 31 cents more than a year ago, according to the AAA.

Flat prices ushered in the first week of spring in a trend that has held for more than a month. For the week, prices moved lower by fractions of a penny, and have increased one cent in the past week.

The nation’s top ten least expensive markets include South Carolina ($2.01), Tennessee ($2.04), Alabama ($2.05), Mississippi ($2.06), Arkansas ($2.08), Texas ($2.09), Virginia ($2.09), Oklahoma ($2.09), Louisiana ($2.10) and Missouri ($2.10).

The nation’s markets that have seen the largest yearly increases include Washington (61 cents), Utah (60 cents), Alaska (58 cents), Idaho (56 cents), New Jersey (55 cents), Oregon (54 cents), Hawaii (51 cents), Montana (44 cents), Pennsylvania (43 cents) and Connecticut (40 cents).

Meanwhile, the average price of diesel fell 2.5 cents to $2.539 per gallon. Diesel is now 42 cents higher than a year ago, according to the U.S. Energy Information Administration.