The price of gas in Tennessee fell for the 20th straight day Sunday and it's a trend likely to continue this week, according to AAA. This may mean per-gallon prices hit will an annual low a little more than a week before a fuel tax increase goes into effect.

The auto club said the average price for a gallon of regular gas in Tennessee is $2.05, the fifth lowest per-gallon average in the country. Barring unforeseen circumstances, AAA predicts prices will continue to fall this week to hit a 2017 low, just before the state adds four cents back to the total next month.

The IMPROVE Act, Gov. Bill Haslam's transportation improvement plan, includes a phased-in six-cent increase in the state's gas tax. The first four cents will be added July 1 with an additional penny in 2018 and 2019. In exchange, the state portion of the food tax will drop from 5 percent to 4, add a variety of other manufacturing, and excise taxes will be gone.

However, even with a four-cent increase, on current prices, Tennessee would still have some of the most affordable gas in the country.