The familiar customs of Halloween in the United States, from dressing up in costumes to trick-or-treating, from parties to ghost stories, from bobbing for apples to pranks, have origins hundreds, even thousands of years old.

Halloween is a holiday deeply linked to life and death. The history of Halloween is also a history of the religious, political, cultural, social, and even pop culture forces that have helped shape it into its modern incarnation.

The origin of Halloween lies in the Celtic holiday of Samhain Night, or "Oiche Samhain," a celebration of the dead as well as harvest and renewal. The Celts believed that on October 31, the last day of summer, the dead would return to mingle among the living. It was the day the dead transitioned to the underworld. The Druids, Celtic religious leaders, used the presence of spirits to aid in their predictions for the harvest. People lit bonfires to keep the ghosts from possessing them and to comfort the souls of the departed. The Celts doused their own hearth fires before the celebration, and afterwards, relit them from the sacred bonfires. To keep the dead from playing pranks, people gave the Druids food. This is likely part of the origin of trick or treating.

The Romans had conquered Celtic territory by 43 C.E., bringing their own traditions and religious beliefs with them. Feralia was a feast honoring the passing of the dead. There was also a feast to honor Pomona, goddess of fruit trees. Her symbol was the apple, which could be linked to the later tradition of bobbing for apples. In 609 C.E., Pope Boniface IV established a celebration of the Virgin Mary and the martyrs: All Saints Day. Originally this fell in May. In the eighth century, Pope Gregory II moved the date to November 1, but only within Rome. Pope Gregory IV extended that date to all Roman territories in 835 C.E. The Romans wanted to convert the pagans, and their strategy for doing so was to make the Catholic holidays fall on the same day as the pagan ones, which is also how Christmas, originally a pagan midwinter festival, got its date as well. Eventually the Druids had to go into hiding, as Roman missionaries sent back propaganda reports of devil-worship. To this day misconceptions still associate Halloween with evil.

The Mexican holiday the Day of the Dead, Los Dias de Los Muertos was originally an Aztec and Mayan tradition, a tribute to the dead that fell in July or August according to the Gregorian calendar. When the Spanish conquistadores arrived in the 15th century, they moved the date of the celebration of the dead to All Saints Eve and Day. The Mexican Day of the Dead celebrates the return of the Monarch butterflies who migrate to the US and Canada for the summer, and return to Mexico in autumn; the belief that butterflies carried the souls of the dead to the afterlife is an Aztec tradition. In Mexico, families observe the Day of the Dead by decorating the graves of deceased loved ones with flowers. They invite the spirits of the dead into their homes, creating an altar with flowers, pictures, food, and other things the dead person liked. It is a celebration of children as well, a renewal of life. As in the American Halloween, sugary food plays a role; people eat sugar candy shaped into skulls and pan de muerto (bread of the dead).

Another origin of trick or treating may have been the European tradition of "souling." On November 2 , people would go to each other's homes and beg for "soul cakes," which were cakes baked with currants. This tradition carried over into English Halloween celebrations. In England, people celebrate Mischief Night on November 4, when pranks are carried out. Most notably, the English celebrate Guy Fawkes Day or Bonfire Night on November 5. Bonfire Night marks the foiling of a Catholic plot to blow up King James I and the Protestant aristocracy in the Parliament building in 1605. Guy Fawkes, one of the conspirators, was discovered and confessed the plot. People burn effigies of Guy Fawkes in what could be a subconscious throwback not only to the Celtic bonfires of Samhain, but additionally to the pagan harvest festival Lammas, which involved the burning in effigy of the harvest god (sometimes known as "John Barleycorn," immortalized in John Burns' poem of the same name).

October 31 also marks the date in 1517 when German scholar Martin Luther published his 95 points criticizing the Catholic church, which many felt had grown power hungry and decadent. This event kicked off the Protestant Reformation. In Catholic tradition, bells were rung on All Saints Eve to comfort souls in purgatory. During the Protestant Reformation, this and other Catholic practices were banned; in 1548 King Edward VI forbade the ringing of the bells on All Saints Eve.

In the seventeenth century, the Puritans, who objected to the power the monarchy had over religion, fled religious persecution to the New World. In New England, the celebration of All Saints Eve and Day, and the harvest celebration Samhain, was limited by the Puritan belief that holidays were decadent. However, in some areas of the American colonies, European customs and Native American ones began to mingle and formed the seeds of the modern American Halloween. Harvest celebration parties involved telling ghost stories, singing, and dancing. However, it was more a seasonal tribute to the harvest than Halloween as we know it now.

It was in fact the Irish and Scottish who brought Halloween to the United States. In the 1840's Irish immigrants fled the Potato Famine and came to America. The Scottish emigrated for similar reasons, seeking to escape from poverty and the lack of economic mobility in their home country. The Jack O' Lantern comes from an Irish story about a man named Jack who tricked Satan up into a tree, then carved a cross on it, trapping him there. In some accounts, Satan is cursed to wander between heaven and hell, welcome in neither, and the jack o' lantern is the lamp he carries, a hollow turnip with a candle inside. Scottish tradition involves Dirge Loaves, which are similar to the European soul cakes, pranking, and the carving of turnips. The Scottish harvest festival honors the return of the Cailleach Bhuer, the blue hag of winter. The last sheaf of corn from the harvest is dedicated to her.

Pumpkins themselves are of North American origin, and have been growing there for 5,000 years. In 1584 a French explorer, Jacques Cartier, found what he called "gros melons" in the St. Lawrence region. The English modified the name to "pompions," which later became "pumpkins." Pumpkin carving is derived from the practice of putting a candle within a hollowed out turnip to ward off evil spirits combined with the Irish story of Jack and the devil.

The early 20th century saw the start of the familiar version of Halloween as it is now observed, with postcards, decorations, and figurines, although it was still primary a holiday practiced by adults. It wasn't until after World War II that mass-produced costumes and huge candy sales joined the holiday. In the post-war prosperity and suburban boom, Halloween flourished as a children's holiday that retained only traces of its origins.

In America, pop culture played a strong role in popularizing Halloween, and carrying the modern American Halloween customs to other countries. Orson Welles' terrifying mock radio broadcast, The War of the Worlds, aired on October 30, 1938 in honor of Halloween. Although the broadcast stated the events were not true, many missed the announcement. While it did not in fact tip off a full nationwide panic as is commonly believed, it certainly alarmed great numbers of people.

It's the Great Pumpkin, Charlie Brown, the famous "Peanuts" special, first aired on CBS on October 27, 1966. It has rerun almost every year since, and is as deeply a part of Halloween as the traditions the film depicts. The Great Pumpkin is a snapshot of an American suburban Halloween, with trick-or-treating, apple-bobbing, costume parties, and pumpkin carving. Of all the children, Linus seems the only one sensitive to the Celtic origins of Halloween. The Great Pumpkin, who chooses the most "sincere" pumpkin patch to rise from, can be read as a nod to harvest celebrations, some sort of harvest god. The tone is innocent; in all the "Peanuts" works there are no adults.

The 1960's and early 70's were a time of social unrest and upheavel. As the baby boomers came of age and questioned the culture they had been raised within, so popular culture shifted towards telling scary stories more appropriate for adults and older teens than children, reflecting the shift of the holiday from a children-only club. Rumors of razor blades in apples began to arise starting in the 1960's, further restricting children's activities.

Alfred Hitchock's Psycho came out in 1960, but the start of "slasher" movies really began with films such as Tobe Hooper's Texas Chainsaw Massacre in 1974 and John Carpenter's Halloween in 1978. Both of these helped kick start the heyday of horror films in the 1980's such as Friday the 13th and the Nightmare on Elm Street series. Such films tap into the thrill of being scared, as well as fears of mortality. Horror movies offer their own kind of comfort as the viewer "survives" watching the film, while countless characters die onscreen.

In 1982, Steven Spielberg's movie E.T. also captured a snapshot of contemporary Halloween and like The Great Pumpkin, provided images almost as well known as the traditions themselves. As in The Great Pumpkin, Halloween in E.T. has an innocent mood. Adults are present and play a big role, however. Elliott's mother is shown in costume for a Halloween party. A mysterious government agency looking for the alien comes across as the terrifying threat, not the alien himself or the bloody or frightening costumes the children wear. Halloween is presented as a night of fun for children, and even provides a haven as the use of costumes allows Elliott to conceal his alien friend. Grownups share in the fun, but as in The Great Pumpkin, the children rule for the night.

Halloween entertainment isn't just limited to television and movies. In New York City, the Village Halloween Parade is a major event. It started in 1973 with just a few hundred people, the concept of a local puppeteer. It has since grown; latest statistics put the costumed participants count at 50,000 and spectators in the millions. It is covered by the media nationwide and worldwide. The gay community in particular has embraced the parade as a chance to openly express their identity. Costuming, for anyone, is a chance for creative expression, role playing, trying out different identities, or to challenge what scares us by dressing up as monsters of all kinds and definitions. Satire and political expression plays a role as well; at the Village Parade, and elsewhere, at Halloween there are always a number of politically-themed costumes.

The holiday continues to struggle with cultural and political forces. In 1950 the Senate Judiciary Committee tried to rename Halloween "Youth Honor Day" in order to counteract the rash of destructive pranks. Even something as benevolent as UNICEF came under suspicion. UNICEF, the United Nations Children's Fund, was founded in 1950 to aid children in poverty. But one urban legend holds that in the paranoia of the Cold War, some schools banned the ubiquitous UNICEF boxes as a communist plot. In recent years, some communities leery of the pagan undertones have banned the word "Halloween" in schools and public spaces, instead using "Harvestfest" (which ironically states the holiday's pagan origins outright).

In the "Peanuts" special, Linus' normally crabby big sister Lucy teases and scolds him for his choice to stay in his pumpkin patch because, she says, he'll miss out on the fun. One sibling looks to the familiar rituals of their culture, the other wonders what lies behind them, and ends up inventing, or reclaiming, his own.

Meanwhile, Snoopy, ever the maverick, goes far beyond trick-or-treating. He not only gets into costume as the World War I flying ace, but indulges in some role playing. Violet holds a Halloween party complete with pumpkin carving and bobbing for apples. Pig Pen hopes his ghost costume will conceal his identity, but it destined for disappointment. The characters each get something different out of Halloween, celebrating as they see fit.

Halloween, with its blend of many different customs, is not only the chance to be whatever you want, it becomes whatever you want it to be.