Circle K is offering a 40-cent discount on all types of gas for National Fuel Day, but there's a catch: the discount is only available for three hours.Drivers must visit Circle K between 4 p.m. and 7 p.m. on Thursday to get the discount, which will be applied directly at the pump.Circle K has thousands of locations across the country. Click here to find your nearest location. RELATED STORY | Low gas prices expected to fuel record-breaking 2024 Thanksgiving travel weekThe discount comes as people prepare for one of the busiest travel seasons of the year.An estimated 79.9 million Americans are expected to travel at least 50 miles from home during the week of Thanksgiving, according to the auto club AAA. Most of them 71.7 million will be traveling by car, AAA estimates.Lower gas prices appear to be helping drive the travel boom. As of Thursday, the average price for a gallon of gas in the U.S. is $3.06, a drop of 20 cents from this time last year.RELATED STORY | Americans 'enthusiastic' about traveling this holiday seasonPeople in Oklahoma are currently paying less for gas than others across the country. The average price for a gallon of regular unleaded in the state is $2.56. Unfortunately, there are no Circle K locations in Oklahoma.California and Hawaii have the highest average gas prices, at around $4.50 per gallon of unleaded. There are Circle K locations in both states.