Four years ago, President Ronald Reagan galvanized public support to battle "terrorists and subversives just two days' driving time from Harlingen, Tex."

Reagan's ambassador to the United Nations, Jeane J. Kirkpatrick, called Central America "the most important place in the world for the United States today." The focal point for a bitter ideological struggle between conservatives and liberals, Central America received more than $9 billion in U.S. military and economic aid during the 1980s.

But in the past 18 months, the swift end of the Cold War and the electoral defeat of the Sandinistas in Nicaragua, followed by the Persian Gulf crisis and continuing domestic budget woes, have made the drive from Central America to Harlingen seem much longer.

With the exception of El Salvador -- where Congress is still moving toward substantial aid cutbacks -- Central America is returning to its more traditional position of obscurity on the list of U.S. foreign policy concerns, a fact that several Central American leaders noted with alarm in recent United Nations speeches.

And historians and scholars are beginning to debate the value of a decade-long struggle that so far has cost the lives of about 70,000 Salvadorans, 80,000 Guatemalans and as many as 40,000 Nicaraguans.

There is little doubt that the region no longer mobilizes the faithful in this country. Politicians, interest groups and academics, who once built careers and multimillion-dollar organizations on both sides of the struggle, now say the war for American hearts, minds and pocketbooks they waged so ardently during the 1980s is over.

"There was a time three to five years ago when any appeal related to Central America could expect to encounter tremendous support from the donor," said Mal Warwick, a San Francisco fund-raiser for liberal groups. "That is no longer the case."

Central America "is not working in the mail," agreed Bob Billings, legislative director for the American Conservative Union. It is no longer a "hot button issue," he said. "It's been close to two years since we've done a Central American mailing of any kind."

For Congress, Central America, with Nicaragua leading the way, was the single most divisive foreign policy issue during the 1980s. Nearly 40 floor votes in the House, and more than a dozen in the Senate, were taken on aid to the anti-Sandinista contra rebels. During much of the decade, aid to El Salvador was the subject of repeated bitter debates over human rights abuses.

Such was its vision of the region as the major test of U.S. resolve to fight communism that the Reagan administration skirted political ruin, with the Iran-contra affair, in its zeal to aid the anti-Sandinista rebels.

For Reagan, the issue was that "we had to stop the Soviets from meddling in our own region . . . or our credibility would be diminished elsewere," said Mark Falcoff, resident scholar with the conservative American Enterprise Institute.

Whether the region is better off as a result, Falcoff said, is a difficult question. The Central American countries "got through the decade with a lot more aid than they would have," he said. Also, the Reagan policy was "the first time in the history of U.S.-Central American relations when all the colonels knew that the United States didn't want them running their governments," Falcoff said. Military dictatorships that began the decade were at least nominally replaced with elected, civilian governments.

But Robert J. Kurz, an analyst with the liberal Brookings Institution, said that "on balance, no one talks about the '80s as a decade when education, literacy, health care or housing came to Central America. Despite the billions spent . . . {and} the great number of people who died . . . the plight of the average Central American is pretty much where it was when the decade began."

Given the results of such intense U.S. interest in the region, he said, "less U.S. attention is probably positive" so long as it does not mean "going from full throttle to full stop" in terms of U.S. aid.

Lower U.S. interest in the region already appears to be translating into reduced U.S. economic assistance, several diplomats and experts said, worsening the economic effects of recent sharp rises in oil prices and, in some cases, the cumulative effects of a decade of civil war.

The Bush administration focus on trade and private sector initiatives will help the region, experts said, but they can not substitute for direct development aid.

"When we ask for aid, the administration points to the budget problems," Costa Rica's ambassador to Washington, Gonzalo J. Facio, said in an interview. "The interest {in Central America} is just not there. It makes my life more difficult," he said.

U.S. economic aid to Costa Rica, repeatedly praised by the Reagan and Bush administrations as a model democracy, has dropped from $217 million in 1985 to $65 million requested by the administration for 1991. The overall 1991 economic assistance request for the 29 million people of Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama and Belize is 30 percent less than the $1.2 billion sent there six years ago.

The 1991 request includes $200 million for Nicaragua that many observers believe will drop substantially in future years. Panama, invaded in 1989 by U.S. forces, and budgeted for $442 million in aid last year, is not scheduled to receive any assistance in fiscal 1991.

Even El Salvador, with its devastated economy and still-raging war, is scheduled for reduced assistance. The administration has asked for about $370 million in military and economic assistance, compared to about $570 million in 1985.

The administration has asked for $132.5 million for Honduras, which received $224 million in economic aid in 1985, and $120 million for Guatemala, down $57.5 million from its peak in 1987.

The electoral defeat of Nicaragua's leftist Sandinista government was a major political victory for the Bush administration. But Nicaragua's economy, ruined by a decade of mismanagement, a U.S. economic embargo and the contra war, was destroyed in the process, while the Sandinistas remain a powerful political force.

Nicaragua's economic troubles prompted Sandinista leader Daniel Ortega to tour Germany, Italy and Sweden last month seeking economic aid for the U.S.-backed government of President Violeta Chamorro.

Liberal and conservative experts say they expect the decline in U.S. aid interest in the region to continue.

Central America "is not a big political issue in the United States any more," said Elliott Abrams, who as assistant secretary of state for Latin America in the Reagan administration served as point man for the Cold War-driven policy. "The level of attention devoted to Central America in the '80s was the product of a special set of circumstances which were absolutely unique and no longer exist."

Abrams's successor in the Bush administration, Bernard W. Aronson, said it is "true that Central America is not a hot-button issue anymore, but that's a sign of progress -- of moving to bipartisan policy in the United States and cooperation instead of confrontation with the Soviet Union. But that doesn't mean the region is receiving less attention or that it has slipped off the radar screen."

In terms of overall U.S. interests, said William Goodfellow, director of the liberal Central for International Policy, "The fact is, the {Central American} region is not that important. Until {Nicaraguan dictator Anastasio} Somoza was carried out {in 1979}, nobody paid any attention to Central America. We weren't putting any money into there in the late 1970s."

"Now that the communist bogeyman is gone," he said, Central America "will be as quickly forgotten as it quickly emerged. Nobody's going to care at all."