An estimated 1,873 fewer people died in U.S. traffic accidents in 1981, according to a federal tally. It was the first significant drop in the toll since the Arab oil boycott of 1973-74.

Safety experts credited the reduction in highway carnage at least in part to the nation's severe economic recession, which they speculate may have cut down use of automobiles.

But Alan Hoskin, statistical department manager for the National Safety Council in Chicago, said the council's figures indicated driving mileage in 1981 had gone up, not down. "Probably a lot of little things and no one big thing" produced the decline in deaths, Hoskin said.

Some highway officials suggest that tougher drunken driving laws and child restraint laws and a rise in the legal drinking age in some states has cut the toll.

According to estimates by the National Highway Traffic Safety Administration (NHTSA), 49,218 persons died in street and highway traffic accidents in 1981, compared with 51,091 in 1980, a 3.7 percent drop. The death toll had dropped from 54,052 in 1973 to 44,525 in 1975 as gasoline prices shot up and the 55 mph speed limit came into effect, but the annual traffic death figures immediately began climbing back up.

In 1980, the upward trend halted, with the death toll virtually unchanged from 1979.

Ben Kelley, senior vice president of the Insurance Institute for Highway Safety, cautioned that it was difficult to explain the 1981 drop, but he said worsening economies have led to a reduction in driving. "You have less money, so less driving, less gas, less entertainment, less driving by kids," he said.

Kelley and other safety experts also mentioned the possible impact of publicity about stricter drunken driving laws in some states and new laws passed in about 20 states in the last three years requiring children to be strapped in while riding. Candy Lightner, president and founder of Mothers Against Drunk Driving, said in a telephone interview from Sacramento, "I think we had something to do with it; there was a part we played in heightening awareness."

Police in California, Illinois, Maryland and other states have credited publicity about new drunken driving laws and increased use of roadblocks and free taxi service for drunks for a decline in traffic deaths over the New Year's holiday.

But Lightner said that once potential drunken drivers begin to realize that undermanned police departments have little chance of catching them, they begin to take chances again despite tougher penalties. In other countries that have passed stiffer drunken driving laws, she said, "You had an improvement in the first six months to a year, and then it goes up again."

Clarence Ditlow, director of the Center for Auto Safety in Washington, said the new child restraint laws may have lessened the risk for children, but he decried loopholes in many of the new state laws that allow the child to ride without a seatbelt if he or she is being held by an adult. "That just makes it worse," he said.

The national death toll figures compiled by the National Center for Statistics and Analysis under the NHTSA are based on state reports of fatalities on roadways and do not include parking lot and other off-street auto accidents that the National Safety Council adds to its totals, said Grace Hazzard, data retrieval specialist with the center.

According to the figures provided by Hazzard, traffic deaths in 1981 increased over 1980 deaths in only three months--January, February and April. The March figures for the two years were almost the same, but the later months of 1981 showed a consistent decline, at the same time that the economy was worsening and publicity about new drunken driving laws was increasing.

The largest declines were in June, with an 11 percent drop, and in August, a 10 percent drop.

Sidney Port, a professor of mathematics at the University of California at Los Angeles, said the drop of 1,873 in a year is statistically significant and has to be caused by some factor other than chance.