If you’re planning to travel over the upcoming holiday weekend you better make sure you can find some gas!

The national average price for a gallon of regular stands at $3.10, the highest since October 2014. It’s also 2% higher than it was on Memorial Day, and 42 percent higher than it was a year ago. At the same time, many gas stations don’t have gas at all.

It has nothing to do with the price, or even the supply, of gasoline—it’s due to a shortage of tank truck drivers coupled with rising demand that is causing supply chain bottlenecks and shortages.

Experts add that a number of stations are reporting that they are simply not able to get gas delivered for any price. This comes as the AAA forecasts that 43.6 million Americans will travel by car this Fourth of July weekend.

CNN