COLUMBUS, Ohio (AP) - Rising prices at the gas pump appear to be having at least one positive effect: Traffic deaths around the country are plummeting, just as they did during the Arab oil embargo three decades ago.

Researchers with the National Safety Council report a 9 percent drop in motor vehicle deaths overall through May compared with the first five months of 2007, including a drop of 18 percent in March and 14 percent in April.

Preliminary figures obtained by The Associated Press show that some states have reported declines of 20 percent or more. Thirty-one states have seen declines of at least 10 percent, and eight states have reported an increase, according to the council.

No one can say definitively why road fatalities are falling, but it is happening as Americans cut back sharply on driving because of record-high gas prices.

Fewer people on the road means fewer fatalities, said Gus Williams, 52, of Albany, Ga., who frequently drives to northern Ohio. "That shows a good thing coming out of this crisis." He has also noticed that many motorists are going slower.

The federal government reported in April that miles traveled fell 1.8 percent in April compared with a year earlier, continuing a trend that began in November.

Experts say a slumping economy and fuel prices have brought down the number of road fatalities in a hurry.

"When the economy is in the tank and fuel prices are high, you typically see a decline in miles driven and traffic deaths," said John Ulczycki, the council's executive director for transportation safety.

States also cite other factors such as police stepping up their pursuit of speeders and drunken drivers, as well as better teen-licensing programs, safer vehicles and winter weather that kept many drivers at home. The Governors Highway Safety Association also says seat belt use is probably at record levels and will top 90 percent in several states when figures are released later this year.

But the last time road deaths fell this fast and this sharply was during the Arab oil embargo in 1973-1974, when fatalities tumbled 17 percent, from about 55,100 to 46,000; and as states raised the drinking age to 21 in 1982-83, when fatalities fell 11 percent, from roughly 49,300 to 44,000.

Chuck Hurley, a former official with the National Safety Council and the Insurance Institute for Highway Safety, said half of the decline in road deaths during the 1970s was attributed to high gas prices. The remainder was linked to the lowering of freeway speed limits to 55 mph.

Republican Sen. John Warner of Virginia has said Congress might want to consider reimposing a national speed limit.

Hurley, now chief executive of Mothers Against Drunk Driving, said gas prices have helped curb drunken driving, too.

Even considering new safety measures by states, it is now clear that, just like in the early 1970s, motorists are cutting discretionary travel and reducing the kind of late-night outings for alcohol that often lead to deadly accidents, Hurley said.

"People are going home early or stopping by a store and buying a case of beer and taking it home," said Maj. Daniel Lonsdorf of the Wisconsin State Patrol.

Peg Withrow, 48, of Columbus, said she does more walking and has canceled or delayed trips, including a planned visit to see her parents in South Carolina. When she does get in a car, Withrow and her fiancee discuss whether it's cheaper to take a freeway or city streets.

"Before we leave the house, we plan a route," Withrow said as she loaded groceries into her Ford F-250 pickup truck, a vehicle she calls a "gas hog."

Fatality rates have remained relatively flat over the last 15 years or so, totaling 42,642 in 2006, the last year for which complete figures from the National Highway Traffic Safety Administration are available.

Regulators say a better gauge of road fatalities is the number per 100 million miles traveled, a rate that has been declining even as Americans drive more. In 2006, that figure fell to its lowest level: 1.42 deaths.

Yet the drop-off this year is even greater and appears to be accelerating.

Indiana fatalities are down 26 percent and on pace to surpass the lowest level since the state first began keeping records 18 years ago: 792 fatalities in 2002.

Ohio's rate is off 20 percent, and the state recorded just six deaths over the Memorial Day weekend, the fewest in 38 years. Illinois' total also is off 20 percent, and Wisconsin is down about 30 percent.

Preliminary figures show death rates are down 20 percent in Tennessee, 22 percent in New Jersey, 13 percent in Washington state, 11 percent in Florida and 21 percent in New Mexico, where the state effort to cut alcohol-involved fatalities has resulted in a 35 percent decline in such deaths so far this year, from 83 to 54.

After the energy crisis of the 1970s, traffic fatalities gradually crept up in the 1980s as gas prices dropped and speed limits began to rise again.

But the number of fatalities may continue falling if oil futures contracts are any indication. Most energy traders do not foresee a long-term decline in prices, despite a big decrease last week and another one Tuesday.

"People aren't driving as much. We're definitely seeing a difference" in crashes, said Pam Fischer, director of the New Jersey Division of Highway Safety.

On the Net:

National Governors Highway Safety Association: http://www.ghsa.org/

National Safety Council: http://www.nsc.org/

National Highway Traffic Safety Administration: http://www.nhtsa.dot.gov/