Reference: Roundup of Facts/Statistics From the U.S. Census About Halloween in the United States

From the U.S Census:

Dating back 2,000 years to the Celtic festival of Samhain, Halloween is an ancient tradition associated with images of witches, ghosts and vampires. Today, Halloween has evolved into a celebration characterized by child-friendly activities like trick-or-treating, carving pumpkins into jack-o’-lanterns, and dressing in costumes.

The following facts are made possible by the invaluable responses to the U.S. Census Bureau’s surveys. We appreciate the public’s cooperation as we continuously measure America’s people, places and economy.

41.1 million
The estimated number of potential trick-or-treaters in 2017 — children ages 5 to 14.
Source: 2017 Population Estimates, Table PEPASR6H 

120.0 million
The number of potential stops for trick-or-treaters to occupied housing units.
Source: Housing Vacancies and Homeownership, Table 8 

Hauntingly Delicious Economic Statistics

40,411
The number of people employed by U.S. manufacturing establishments that produced chocolate and cocoa products in 2016.
Source: 2016 Annual Survey of Manufactures, NAICS 311351, 311352

991
The number of formal wear and costume rental establishments in the United States in 2016.
Source: 2016 County Business Patterns, NAICS 532220

Scary Places

Tombstone, Ariz. (estimated population 1,296)
Source: 2017 Population Estimates

Yellville, Ark. (estimated population 1,159)
Source: 2017 Population Estimates

Slaughter Beach, Del. (estimated population 234)
Source: 2017 Population Estimates

Scarville, Iowa (estimated population 70)
Source: 2017 Population Estimates