Not long ago, the Day of the Dead festival — aka Dia de los Muertos — was a mystery to most Americans, and even some Mexicans, too.

People who did know about it tended to think it was the Mexican Halloween, which is not true. But in recent decades, this annual observance has spread from its origins, mostly in southern Mexico, to the rest of the country, and into parts of the United States as well.

At first glance, the celebration’s emphasis on skeletons and graves might seem ghoulish. But it’s actually a time when the devout believe their loved ones’ spirits return from beyond to visit them, for one day only each year.

Originally a festival of ancient indigenous cultures such as the Mayans, the celebration’s dates were changed by invading Spanish conquistadors to match their Christian festivals of souls on Nov. 1 and 2 as part of their campaign to stamp out the ancient religions and replace them with Christianity.

Today, celebrations generally start Oct. 31. Nov. 1 is usually the day to celebrate the souls of children, and the Day of the Dead finishes Nov. 2 — All Souls Day. Some villages have their own dates and customs, but they all occur around the same time. Families would typically decorate the graves of their loved ones and spend the night there with food, drink and even bring music to be with them.

The most solemn and distinctive festivals generally take place in areas with large Indigenous populations. The southern Mexican state of Oaxaca and the island town of Patzcuaro are the most legendary for their ancient and colorful traditions.

But nowadays, many other places have also joined the commemoration with parades, decorated altars and costumes. Even Guatemala has its own tradition.

Keep in mind that you should make your reservations months in advance if you want to go to the most popular locations, such as Oaxaca de Juarez, the state capital. Or Patzcuaro. Also note that these famous locales are the most crowded, as more and more tourists descend.

The delightful, 2017, animated Pixar movie “Coco,” about a boy who visits the underworld to find his deceased ancestors, only brought more attention to the celebration.

Oaxaca (pronounced ‘wa-HA-ca’)

Oaxaca de Juarez is tourist central for the vibrant celebrations, with constant parades, processions, concerts, dances and more. Many visitors get their faces painted and enjoy the party atmosphere. Several small towns nearby have solemn commemorations, with families camping out in the cemeteries on decorated graves, and a carnival atmosphere outside the graveyard. These can get very crowded, so be respectful. The city of Oaxaca’s municipal cemetery (panteon) also is decorated with candles and hosts events. (Note that the state is also called Oaxaca.) Make sure to book your lodging far in advance.

Patzcuaro

This colonial city near Lake Patzcuaro, Michoacan, is known for its celebrations. People come from everywhere, leading to overcrowding in recent years. The main plaza is one of the best places in Mexico to buy Dia de los Muertos crafts. The entire region around the lake erupts in celebrations, including the creation of floral arches at the entrance to churchyards, concerts, offerings to the departed and a major cultural festival including paintings and crafts. A ballgame loosely modeled on Mesoamerican ones is also held. Each island and town has its own traditions. Michoacan is also known for its nighttime celebrations called Noche de Muertos on Nov. 1 and 2. The closest big city is Morelia.

Guadalajara

Did you know that Mexico’s second-largest city has the world’s only Dia de Los Muertos theme park? Calaverandia only operates over the holiday period and includes festive lighting, mazes, a stage show, food, decorations and more. It’s in Parque Ávila Camacho. The city also has a major parade and decorations. The artsy town of Tlaquepaque, which has been swallowed up by the Guadalajara municipality, has its own traditions including a parade of “Catrina brides.” About an hour’s drive away, the town of Zapolanejo is also known for its festivities, including building the world’s largest Catrina figurine four years in a row.

Puerto Vallarta

This beach city’s traditions tend more toward the festive and fun variety and less on solemnity, although there are cemeteries you can visit. There’s always a big parade, art displays and music, and locals erect giant Catrinas all along the malecon (ocean boardwalk.) Concerts abound and altars decorate the main plaza. This year, Puerto Vallarta announced its intention of beating out another city in Jalisco to build the world’s tallest Catrina. The most active dates are Nov. 1 and 2.

Baja California

When I started became interested in the holiday 30 years ago, Baja California didn’t have much to offer. With its rural population down south and its close ties to the U.S. up north, kids were more likely to trick-or-treat in costume, celebrating Halloween, than anything else. Commemorations in cemeteries were sparse. Nowadays, there are more observances for those who don’t want to fly anywhere but still be in Mexico. With more people migrating to the border region for jobs, they have brought their traditions with them, but they’re still relatively sparse.

In Rosarito Beach, the venerable Rosarito Beach Hotel is holding a Noche de Catrinas at 6 p.m. Nov. 2 that includes a Catrinas contest, a folkloric ballet, free Catrina makeup, buffet dinner and live music for dancing. Cost for adults is 550 pesos (around $32). Buy on EventBrite.

Los Cabos have a few festivals going, including a “Sea of Offerings” that seems to incorporate a tequila and mezcal festival with Day of the Dead ofrendas.

Guatemala

This nation’s Dia de los Muertos traditions include a festival of enormous kites that attracts visitors from all over Central America. The festival Nov. 1 takes over the normally sleepy Mayan towns of Santiago Sacatepéquez and Sumpango. The kites are built and decorated by organizations and villages and put on display for the crowds that come to admire. They’re so large that they barely fly, but sometimes people can get them off the ground. The kite festival extends to other villages, where children also make and fly kites this day, symbolizing the souls of the departed. People also decorate the graves and tombs of their loved ones nearby.

Calaveras: Decorative skeletons

Ofrenda: An altar specially made for Day of the Dead, usually by loving family members and including the loved one’s favorite things, to help them find their way back home. In some towns, local businesses and organizations also make public ofrendas. Often, home ofrendas might include a pack of cigarettes, favorite foods, a bottle of tequila or mezcal and framed photos. They’re usually decorated with marigolds, cockscomb and stalks of sugar cane.

La Catrina: This is the stately female skeleton figure, elaborately dressed in a long, Victorian-era gown and hat with plumes, who has become a symbol of Mexico in general and Dia de Los Muertos in particular. She was created in 1912 by Jose Guadalupe Posada, a printmaker, political cartoonist and Mexican patriot. La Catrina was immortalized in 1946 in one of Diego Rivera’s best-known murals. In the past few decades, she has taken on even more importance as a symbol of Mexican pride.

Papel Picado: This Mexican art form involves folding and cutting sheets of material into decorative banners. In the past, it was done with paper, however nowadays you’re more likely to see it in more durable plastic. You see these particularly at Dia de los Muertos and also at Christmas.

Pan de Muertos: This “bread of the dead” is a round loaf only baked for the holiday. It will typically have faces or skeletons embedded in it.

Sugar skulls (Calavera de Azucar): These confections made by master craftspeople of boiled sugar paste are generally given as gifts and only made during this time of year.