Gasoline prices are at their highest levels since 2014 and will continue to rise through Memorial Day. With some metro areas across the nation already seeing prices over $3 per gallon, GasBuddy today issued a new study that found the best and worst days of the week to buy gas to maximize savings at the pump and avoid the lines during the busy summer travel season.

“The case of the Mondays” is not a thing when it comes to pumping gas: Monday offers the lowest average gas price in 21 states, making it the best day to fill-up. Friday is the worst day to buy gas in 19 states, having the most expensive average.

'Best Day To Avoid Lines: GasBuddy' also analyzed GasBuddy foot traffic data and found that gas stations across the country are least busy on Sundays, followed by Mondays. Friday is the busiest day.