Two roads and two towns are relevant metaphors for the progress of events in El Salvador.

Begin with La Palma near the Honduran border, a village where government and guerrilla negotiators recently met to talk about ending their war.

The highway from San Salvador, a twisting, pitted track, is heavily traveled these days and that is satisfying to the small farmers. They spread grain across the road, and within an hour or so it has been husked by the traffic of buses, trucks and cars.

The harvest is abundant this year, and the market in La Palma is filled with produce. Horses and burros stand at hitching posts. The little shops have goods to sell. Rock music blares from a disco. Soldiers take the sun in the public square, laughing and flirting with the girls.

There is no gunfire, near or far, and that is a change from the recent past. There is a sense of normalcy in the air, reflected nationally in a turnaround of El Salvador's economic fortunes.

After five years of steep declines in the gross national product, the economy stabilized in 1983 and last year showed signs of growth.

The darker metaphor is the road to Suchitoto. Up this highway, roughly 20 miles from the capital city, one comes to a Bailey bridge guarded by government troops. They politely record the names of all who pass through the checkpoint to enter an eerie no man's land, a place without farmers spreading grain on the road and without vehicles to husk it.

Two or three miles from the bridge, guerrillas in motley costumes emerge from the roadside underbrush to stare without expression at the passing car. One wears a black T-shirt lettered "Black Max." Their comrades, all armed with M16 rifles, appear every few miles right up to the outskirts of Suchitoto. One band, led by a man wearing a red bandana mask, has stopped a truck loaded with farm people. Whether they are being robbed or lectured is unclear. We stop to ask questions but are ordered to move on.

Suchitoto is a virtual ghost town, with dozens of deserted houses and shops, most of them pockmarked by gunfire and many of them used for gun emplacements by government troops.

A few idle men are in the square, complaining of their inability to find farm work. There is no transportation, they say, because the roads are unsafe. At a small pharmacy, the woman proprietor tells of recent fighting, the exodus of friends and relatives and wonders if she should move on; but where would she go?

That, of course, is the question for her country as well: where is it going?

It is a small place and, despite the passions it arouses in the American political community, is hardly a linchpin in the structure of global concerns. Its national budget, for example, is less than half the annual revenues of either the The New York Times or The Washington Post Co. Its Army is about the size of the New York City police force. For more than four centuries it endured the exploitative rule of Spain, military caudillos and financial oligarchs. Only in the past decade has the United States taken much interest in Salvadoran affairs, an interest spurred on the one hand by the murderous tendencies of the old power structure and, on the other, by a Marxist insurgency.

Today, politicians, journalists and American diplomats sketch out a fairly optimistic future for the country but always with the caveats that "you can't be sure of anything" and "no one really knows what tomorrow will bring." It's an impregnable position.

Their recitation of the good news touches on some signs of vigor in the economy, the steady professionalization of the Army, the emergence of democracy in the "kindergarten stage" led by President Jose Napoleon Duarte, a decline in death-squad activities and other human rights abuses, a modest influx of private capital, a falling off of guerrilla military operations, and the beginning of dialogue on a peace agreement.

San Salvador nourishes this positive mood. It has a vitality -- a patina of prosperity -- that contrasts sharply with the seediness of the Nicaraguan capital, Managua. For the middle classes and the more fortunate, there are modern shopping centers, good restaurants, art galleries, impressive residential areas. Joggers in running togs are on the streets and highways at dawn. A country club and a golf course are patronized by, among others, visiting U.S. congressmen.

Scenes in older sections of the city are reminiscent of the Middle Eastern bazaars -- crowded sidewalks, innumerable shops and vendor stalls. The infrastructure -- communications, utilities, transportation -- works sufficiently well that the city has become the regional headquarters for international news organizations. There is little guerrilla terrorism, a tribute, a veteran journalist noted, to the grim efficiency of the right-wing death squads.

It is the right wing -- nameless oligarchs and capitalists aligned with Army factions -- that is more on the mind of Duarte and his U.S. sponsors these days than the guerrillas of the Farabundo Marti National Liberation Front.

Duarte dismisses, almost casually, the possibility of a guerrilla military victory. But the right wing, he says, continually tries to "destabilize" the government and dreams of disposing of him through impeachment or a coup d'etat. A focus of the problem is the National Assembly, where Duarte's allies are outvoted 34 to 26 and where his proposals often are defeated.

This balance could be changed by assembly elections next month. Duarte has a chance of gaining a majority in coalition with other parties. His vice president, Rodolfo Castillo Claramount, describes the coming elections as a "plebiscite by the people. They will decide whether to permit or prevent him from governing during the next three years."

It is clear that the Americans want Duarte to win. He is the edifice around which American policy in El Salvador is built. "The beauty of the present situation," a diplomat observes, "is that Duarte is committed to all those things that are of concern in the United States -- human rights, social justice and peace."

Because of those commitments, says the government's economic minister, Ricardo Gonzalez Camacho, elements in the right wing look on Duarte and his Christian Democratic Party "as if they were communists . . . . But if they the right were to come to power, they wouldn't last three weeks."

Duarte depicts himself as a man of the middle, buffeted by radicals of both the left and the right. For now he is also the man of the hour, the vessel of hope for American policy objectives.