To most Americans, mariachi music is music of the daytime--even, specifically, warm-weather music, associated with sunny, beer-soaked vacations. But a certain strain of mariachi, the ranchera, serves best to illuminate the night: the romance of paper lamps, dancers kicking up dust in unpaved courtyards, lovers in alleyways, memory diffused through drink.

A ranchera song is a love song--sometimes a love song to one's country--accompanied by mariachi music. Literally translated, the term means "ranch music." I first heard rancheras on an all-night bus ride, headed down the Baja. Darkness turned the bus windows into mirrors, and each passenger rocked wearily into his or her own reflection. The fitful passing headlight illuminated stretches of desert outside, landscape as empty as the pause between musical phrases: held breaths between measures of lunatic abundance. In the seats behind me, a father and son played checkers on a small board balanced precariously between them. Occasionally the father, an elegant old man, rose to use the bathroom, and when he returned, the son would ask, "Are you--" and he would interrupt brusquely: "I'm fine," and they would return to their game.

At some point, the son reached over to a boom box and turned it on. A wave of brass and violin filled the cabin, followed by an operatic voice singing, "Es la mujer." Later I would learn the voice belonged to Alejandro Fernandez, son of famous ranchero singer Vicente Fernandez. Just as his father did, Alejandro carries the lush tradition of seductive rancheras with the grace of a back-lot lothario; even the sweep of his hair denotes romance. The intense emotion of rancheras is so compelling because the singer almost always seems about to erupt into a sob, his voice choking up, dense melody caught behind the longing welling up in his throat. On the covers of his albums, Alejandro gazes out of the picture frame in soft focus, his thick eyebrows colliding into a severe line of melancholy. Muy Dentro de Mi Corazon, the 1996 album that was my introduction to him, features Alejandro in a big red bullfighter's bow tie, surrounded by candles. His hands are folded and he looks down at them sadly. One gets the feeling that his lover has just left, and that the priest is just about to approach him with sympathy.

Alejandro is older now--nearly 30--and his newest album, Entre Tus Brazos, attempts to style him a little more to stateside tastes: He sings ballads, and on the cover he wears a ribbed roll-neck. Still, I prefer mariachi.

Mariachi music is so old its origins are lost, although the word itself is documented in native usage as far back as the Spanish conquest of Mexico in 1529. Like American folk music, amateur mariachi often acted as a public political conscience. Radio and recording probably helped formalize the genres, and when movies came to Mexico, rancheras, with their streamlined orchestration, became a favorite for soundtracks, especially to turn up the color of romances. Like darkness, rancheras obscure the hard angles of love and loss, deepening the pleasure of poignancy.

In fact, when my little brother got "married" to his Canadian love in Puerto Vallarta (holding a cere-mony that messy immigration paperwork rendered little more than symbolic at the time), they hired a four-member mariachi band to follow them around. At dusk, in the vine-draped restaurant where we all raised glasses of champagne, the violin became the voice for happy sadness, and the harmonies fractured my steely sisterly resolve not to cry. The night air, warm as a cloak, seemed to urge the melodies on to fluidity. Whenever I caught the eye of one of the mariachi players, he would give me a serious little nod, as if confirming our place in civilization's circle of ritual. After a while I began to feel as if the music was expressing something of my emotions I couldn't verbalize: especially one corny song, "Una Paloma Blanca," which I kept asking the band to play over and over again. Dizzy, sticky with champagne, I listened to the swelling harmonies and watched my brother hold the hand of his love. Around the table, in the candlelight, everyone's eyes were sugared with tears.