The tax per gallon of gasoline in Alabama will increase 6 cents on Sunday as the first rate increase on gas in more than 20 years goes into effect.

The gas tax will increase 6 cents to 24 cents per gallon for gasoline and 25 cents per gallon for diesel.

Ahead of the Sunday, AAA estimated the average gas price per gallon for the state at $2.21 with Tuscaloosa’s average at $2.17. The national average was $2.58 per gallon.

The tax will increase an additional 2 cents annually in 2020 and 2021. In 2021, the tax rate adjustment will be pegged to the percentage change in the yearly average of the National Highway Construction Cost Index. The rate change will be rounded to the nearest whole cent with the increase or decrease not exceeding $.01 per gallon.

State lawmakers approved the increase, called the Rebuild Alabama Act, this spring. The revenue from the tax must be spent on maintenance or construction of roads and bridges and cannot be used for unrelated labor, equipment or structures.

Rep. Bill Poole, a Tuscaloosa Republican, sponsored the legislation.

“Our citizens know we have to do something to address our infrastructure,” Poole told the Associated Press in March.