Booming intrastate trucking and lower production have left the U.S. with the fewest days of supply of heating oil in more than two decades ahead of the winter.

Inventories of diesel used for heating and transportation are enough to meet 31.2 days of demand, that’s the tightest it has been for this time of the year since 2000, according to the Energy Information Administration.

The dearth of supply comes as a global natural gas shortage brought prices for that fuel in the U.S. to a 12-year high earlier this week, motivating some power plants to switch to heating oil. The result will be that Americans that live in part of the Northeast could be strapped with soaring heating costs this winter.

Nymex diesel futures are trading a $2.45 per gallon after jumping to a seven-year high earlier this week.

The squeeze may get worse before it gets better as truck drivers deal with a surge in online shopping and historic delays in the global supply chain. Midwest farmers are out with their tractors harvesting the second largest corn crop ever produced. The timing couldn’t be worse, with many U.S. refineries typically shutting down production to conduct maintenance this time of year.