Oil prices are plummeting around the globe, down 38 percent since July. It's one of the few upbeat developments right now for American consumers.

Back in July, the cost of oil topped $147 a barrel, and some feared it could surge to $200 or more. But on Tuesday it was barely over $91 a barrel.

Who's benefiting?

• Motorists across the country are paying less at the pump than earlier this summer. Although prices have jumped a bit since Hurricane Ike, they are likely to go back down soon, given the big fall in petroleum markets.

• Farmers and large trucking companies are shelling out less for diesel fuel. A gallon that cost $4.85 in mid-July had fallen to $4.10 this week, even after Hurricane Ike. If they continue, reduced fuel costs for farmers and shippers should lower prices for food and for many goods carried by trucks.

• Airlines aren't paying as much now for jet fuel as they did earlier this summer. Again, the decreased price of oil could eventually lead to lower ticket prices and could ease recently imposed charges for extra luggage.

But there also are some drawbacks to falling oil prices.

Energy experts worry that Americans might resume their gas-guzzling ways. Consumers ought to continue conserving gasoline and purchasing more fuel-efficient vehicles. After all, the dip in U.S. gasoline demand this summer quickly helped lower oil prices.

Economists point out that petroleum demand also is falling because of weakened economies around the world.

Still, the lower cost of gasoline is saving American consumers billions of dollars. Just as sharply higher costs for oil earlier this year damaged the U.S. economy, lower prices in the coming months could help breathe new life into it.