The celebration that eventually became Halloween traces back about 2,000 years to the ancient Celtic festival of Samhain, observed around November 1 in regions that are now Ireland, the U.K., and northern France.

Quick Scoop

  • The earliest roots of “the first Halloween” come from Samhain, a Celtic new-year-and-harvest festival celebrated roughly 2,000 years ago.
  • In the 7th–8th centuries, Christian leaders established All Saints’ Day on November 1, and the evening before became known as All Hallows’ Eve, later shortened to Halloween.
  • The modern, costume-and-trick-or-treat style Halloween really took shape in the 19th–20th centuries, especially in the United States, rather than on a single exact “first” date.

Was There a Single “First Halloween”?

Historians do not agree on one exact calendar date for “the first Halloween” because the holiday evolved from older seasonal and religious festivals over many centuries. Instead, most point to Samhain as the starting point, then track how Christian and later American traditions layered on top of it.

So, in everyday terms:

  • First ancestor festival: Samhain, about 2,000 years ago in Celtic Europe.
  • First “All Hallows’ Eve”: by the Middle Ages, after All Saints’ Day moved to November 1.
  • First recognizably modern Halloween (parties, costumes, trick-or-treating): late 1800s–early 1900s, especially in North America.

Today, when people ask “when was the first Halloween,” most historians answer: it grew out of Samhain about two millennia ago , then slowly turned into the October 31 Halloween celebrated now.

Information gathered from public forums or data available on the internet and portrayed here.