Halloween may be over, but it brought with it an unexpected treat for consumers: the national average price of gas fell to $2.995 on Saturday for the first time in four years.

U.S. average prices for gas fell 33 cents to finish out October at $3 per gallon, and by Saturday it had dipped below that threshold as demand slows down, surprising economists. Globally, prices had been on an upward trend as developing countries drove demand with tens of millions of new cars, and as instability in the Middle East threatened supplies, according to the Associated Press.

The prices defied expectations because drillers have been able to find new sources of oil, and the conflict in the Middle East hasn’t affected the flow of crude oil. However, economists believe that seasonal shifts and other outside forces will soon bring those average prices back over $3.

But the United States is on track to post its lowest annual gas price average since 2010, and next year’s prices could dip even further.

The low prices have been a few months — even years — in the making, Oil plummeted from $107 per barrel in June to just about $81, all while U.S. output has jumped 70 percent since 2008. A sluggish global economy has further put a damper on prices.

The push to more fuel-efficient vehicles has also stunted the prices of gasoline. This has helped prevent gas prices from rising even when the U.S. economy strengthens and pushes fuel demand up.

Last year’s average stood at $3.51 per gallon. That means the new prices will save the average American household $50 per month, and will save the economy as a whole $187 million per day. It will also help with profits for companies that rely on deliveries or sales calls, such as shippers and airlines.

At $3.73 per gallon, milk is now more expensive than gasoline — for the first time since 2011.